CN-121983205-A - Geotextile reverse filtration layer design method for enhancing silt reverse filtration safety

CN121983205ACN 121983205 ACN121983205 ACN 121983205ACN-121983205-A

Abstract

The invention relates to the technical field of porous material physical property analysis and geotechnical engineering reverse filtration design, in particular to a geotechnical fabric reverse filtration layer design method for enhancing the reverse filtration safety of silt, which comprises the steps of obtaining engineering silt parameters; calculating the maximum value of the hydraulic performance parameter of the material of the reverse filter layer based on a filter layer matching algorithm, analyzing actual engineering conditions, calling a material database to obtain material parameters, searching and determining reverse filter layer alternative materials meeting the conditions in the material database according to the filter layer matching algorithm, carrying out a long-term clogging test on the reverse filter layer alternative materials to obtain the clogging performance index of the material of the reverse filter layer, establishing a clogging risk assessment model to evaluate the clogging resistance of the material, and sequencing the reverse filter layer alternative materials according to the clogging resistance to determine the reverse filter layer materials to generate a geotextile reverse filter layer design scheme. The invention solves the technical problem of designing the geotextile reverse filtering layer of the silt foundation.

Inventors

CHEN WENLIANG
FANG XUHUI
XU JIAHAO
ZHANG XU
Fu Wangbin
QIU SIYAN
CHEN XIULIANG
YU YIMING
ZHANG CHAOJIE
XU JIANXIN
Ge Shilei
CHEN MINGZHE

Assignees

浙江广川工程咨询有限公司

Dates

Publication Date: 20260505
Application Date: 20260407

Claims (8)

1. The geotextile reverse filtration layer design method for enhancing the reverse filtration safety of the silt is characterized by comprising the following steps of: Calculating the maximum value of hydraulic performance parameters of the material of the reverse filter layer based on a filter layer matching algorithm, wherein the maximum value comprises the maximum value of equivalent aperture under tensile strain of geotextile of the reverse filter layer and the minimum value of vertical permeability under long-term load; Analyzing actual engineering conditions, calling a material database to obtain material parameters, and searching and determining a reverse filter layer alternative material meeting the conditions in the material database according to a filter layer matching algorithm; And sequencing the alternative materials of the reverse filtering layer according to the anti-clogging performance, determining the material of the reverse filtering layer, and generating a geotextile reverse filtering layer design scheme.
2. The geotextile reverse filter design method for enhancing the reverse filter safety of silt soil according to claim 1, wherein the filter matching algorithm comprises: The characteristic particle size of the silt and the equivalent pore diameter of the inverse filter layer geotextile under tensile strain should satisfy the following relationship: ; Wherein the method comprises the steps of Is the equivalent aperture of the geotextile under tensile strain; Is the characteristic particle size of the silt; B is a soil conservation coefficient, wherein the soil conservation coefficient B is selected to be a preset value according to the soil type, the non-uniformity coefficient and the compactness of the soil to be protected under the condition of still water or laminar flow; the perpendicular permeability coefficient of the silt permeability coefficient and the reverse filter layer geotextile under the long-term load effect should satisfy the following relationship: ; Wherein the method comprises the steps of The vertical permeability coefficient of the geotextile under the long-term load action is a preset safety coefficient; is the permeability coefficient of the soil to be protected.
3. The geotextile reverse-filter design method for enhancing the reverse-filter safety of the silt soil according to claim 1, wherein the step of searching and determining the reverse-filter alternative materials meeting the condition in the material database specifically comprises the following steps: Acquiring performance parameters of a reverse filtering layer material by collecting the performance parameters of the existing material, testing and measuring the performance parameters of the material, and the like, and establishing a material database, wherein the material database stores various specifications of various reverse filtering layer materials and corresponding performance parameters thereof, including equivalent pore diameters of geotextiles under tensile strain, thicknesses of geotextiles under 2kPa pressure, vertical permeability coefficients of geotextiles under the action of load, compressive creep thicknesses of geotextiles under the normal stress and the design life of the geotextiles, and vertical permeability coefficients of geotextiles under the action of long-term load; Analyzing the tensile strain action type and the tensile strain level of the reverse filtering layer in an actual engineering environment, and calling a material database to obtain the equivalent aperture of the geotextile under the tensile strain condition; Based on the long-term normal stress and engineering design age, a material database is called to obtain the thickness of the geotextile under the pressure of 2kPa, the vertical permeability coefficient of the geotextile under the load and the compressive creep thickness of the geotextile under the design normal stress and the design life; taking the maximum value of the equivalent pore diameter under the tensile strain and the minimum value of the vertical permeability coefficient under the long-term load as search conditions; Traversing the material database, comparing the equivalent pore diameter under the tensile strain condition and the vertical permeability coefficient under the long-term load action of each material in the database with the search condition, and screening out the material of which the equivalent pore diameter under the tensile strain condition is smaller than the maximum value of the equivalent pore diameter under the tensile strain condition and the vertical permeability coefficient under the long-term load action is larger than the minimum value of the vertical permeability coefficient under the long-term load action; All the screened materials are combined into a list as the material of choice for the counter-filter layer.
4. A geotextile reverse filtration layer design method for enhancing the reverse filtration safety of a silty soil according to claim 3, wherein said step of calculating the vertical permeability coefficient of the geotextile under the long term load comprises: taking the long-term normal stress and engineering design age as query conditions; Based on the query conditions, searching and calling the thickness of the geotextile under the pressure of 2kPa, the compressive creep thickness of the geotextile under the normal stress and the design life, which are matched with the query conditions, in the material database, and calculating the thickness compressive creep reduction coefficient; Based on the environmental conditions of engineering application, the total reduction coefficient of the permeability index of the geotextile is calculated by calling the reduction coefficient of the geotextile subjected to clogging, the reduction coefficient of the fabric caused by creep, the reduction coefficient caused by the extrusion of adjacent soil materials into the fabric pores, the chemical clogging reduction coefficient and the biological clogging reduction coefficient in the material database; Calculating to obtain the long-term performance reduction coefficient of the geotextile; Based on the long-term normal stress of the reverse filtering layer, the vertical permeability coefficient of the geotextile under the load action is called in the material database; Calculating to obtain the vertical permeability coefficient of the geotextile under the long-term load effect; the calculation formula is as follows: ; Wherein the method comprises the steps of The coefficient of vertical permeability of the geotextile under the long-term load effect is C is the coefficient of long-term performance reduction of the geotextile; the vertical permeability coefficient of the geotextile under the action of corresponding load; the thickness compression creep reduction coefficient of the geotextile; The total reduction coefficient of the permeability index of the geotextile is obtained; The compressive creep thickness of the geotextile under the design normal stress and the design life is given; Is the thickness of the geotextile at a pressure of 2 kPa; The coefficient of the geotextile is reduced by silting; A reduction coefficient that reduces fabric porosity for creep; a reduction coefficient caused by the extrusion of adjacent soil materials into the pores of the fabric; Is a chemical clogging reduction coefficient; is a biological clogging reduction coefficient.
5. The geotextile reverse-filtering layer design method for enhancing the reverse-filtering safety of silt soil according to claim 1, wherein the step of obtaining the clogging performance index of the reverse-filtering layer material by performing a long-term clogging test comprises the following steps: Developing a long-term clogging test, determining gradient ratio GR according to SL235-2012 standard, calculating permeability coefficient KR, and the calculation formula is as follows: ; Wherein KR is the osmotic coefficient ratio; The permeability coefficient is common to geotextiles and soil materials 25mm above the geotextiles.
6. The geotextile reverse filtration layer design method for enhancing the reverse filtration safety of silt soil according to claim 1, wherein the method is characterized by establishing a clogging risk evaluation model and evaluating the clogging resistance of a material, and specifically comprises the following steps: The gradient ratio and the permeability coefficient ratio are used as the clogging risk evaluation index, a clogging state discrimination threshold is set, the clogging risk evaluation index is compared with the clogging state discrimination threshold to determine the clogging risk grade, a quantitative grading standard is set for the clogging risk grade, the weight of the clogging risk evaluation index is set, and the clogging resistance score of the material is calculated by a weighted grading method.
7. The geotextile reverse filtration layer design method for enhancing the reverse filtration safety of silt soil according to claim 1, wherein the determining of the clogging risk level by comparing the clogging risk evaluation index with the clogging state discrimination threshold value specifically comprises: The gradient ratio is compared with a first gradient ratio preset threshold, if the gradient ratio is smaller than the first gradient ratio preset threshold, the gradient ratio clogging risk level is determined to be a low risk level, if the gradient ratio is not smaller than the first gradient ratio preset threshold, the gradient ratio is compared with a second gradient ratio preset threshold, the second gradient ratio preset threshold is larger than the first gradient ratio preset threshold, and if the gradient ratio is larger than the second gradient ratio preset threshold, the gradient ratio clogging risk level is determined to be a high risk level, and if the gradient ratio is between the first gradient ratio preset threshold and the second gradient ratio preset threshold, the gradient ratio clogging risk level is determined to be a medium risk level; The method comprises the steps of comparing the permeability coefficient ratio with a first permeability coefficient ratio preset threshold, determining the permeability coefficient ratio clogging risk level as a high risk level if the permeability coefficient ratio is smaller than the first permeability coefficient ratio preset threshold, comparing the permeability coefficient ratio with a second permeability coefficient ratio preset threshold which is larger than the first permeability coefficient ratio preset threshold if the permeability coefficient ratio is not smaller than the first permeability coefficient ratio preset threshold, determining the permeability coefficient ratio clogging risk level as a low risk level if the permeability coefficient ratio is larger than the second permeability coefficient ratio preset threshold, and determining the permeability coefficient ratio clogging risk level as a medium risk level if the permeability coefficient ratio is between the first permeability coefficient ratio preset threshold and the second permeability coefficient ratio preset threshold.
8. The geotextile reverse-filter design method for enhancing the reverse-filter safety of silt soil according to claim 1, wherein the sequencing of the reverse-filter candidate materials according to the anti-clogging performance, determining the reverse-filter material, comprises: And selecting the most ordered alternative material of the reverse filter layer as the reverse filter layer material, and generating and outputting the reverse filter layer design scheme.

Description

Geotextile reverse filtration layer design method for enhancing silt reverse filtration safety Technical Field The invention relates to the technical field of porous material physical property analysis and geotechnical engineering reverse filtration design, in particular to a geotechnical fabric reverse filtration layer design method for enhancing the safety of silt reverse filtration. Background In geotechnical engineering, porous materials such as geotextiles are often used to reverse-filter and protect fine-grained soil bodies such as silt. The evaluation of the soil conservation, water permeability and clogging resistance of the porous material when the porous material contacts with soil is a key for ensuring the reverse filtration safety of the porous material. The silt particles are fine and uniform, the grading is poor, the filter layer is blocked and the filter layer is invalid due to improper reverse filtration and selection of the geotextile, and the permeation damage is caused. Therefore, the silt soil needs to put more strict requirements in the design of the reverse filtration layer relative to other soil so as to ensure the effective reverse filtration of the geotextile. The existing reverse filter layer design method has the following limitations that firstly, the influence of tensile strain of geotextiles on equivalent aperture of the geotextiles in an actual engineering environment is not considered, secondly, the selected geotextiles have a common vertical permeability coefficient, the vertical permeability coefficient under the load effect of being more attached to an actual state is not adopted, meanwhile, the influence of thickness variation of the geotextiles caused by compression creep in normal stress and long-term service on the vertical permeability coefficient is ignored, thirdly, in the aspect of anti-blocking evaluation, the gradient ratio obtained by a blocking test is relied on, but the index is difficult to distinguish the blocking of the geotextiles and the soil body, misjudgment is easy to cause, and the limit value of the gradient ratio aiming at silt is still controversial at the present, so that the evaluation method is insufficient in accuracy and reliability. Therefore, it is necessary to establish a geotextile reverse filtration layer design method suitable for silt reverse filtration, and the method needs to better reflect the influence of factors such as tensile strain, normal stress, long-term clogging and the like on the geotextile reverse filtration under actual engineering conditions, so as to perform safe and reliable analysis and evaluation on the long-term reverse filtration performance of the geotextile in the actual engineering environment. Therefore, a geotextile reverse filtration layer design method for enhancing the reverse filtration safety of the silt is provided. Disclosure of Invention The invention aims to provide a geotextile reverse filtering layer design method for enhancing the reverse filtering safety of silt, which comprises the steps of correcting the existing reverse filtering criterion to establish a geotextile reverse filtering criterion which can more truly reflect the actual working condition, and forming a corresponding geotextile reverse filtering layer material selection method based on the criterion. The reverse filtration criterion established by the method considers the change of the equivalent aperture of the geotextile under the tensile strain of the actual engineering in terms of soil conservation, adopts the vertical permeability coefficient more in line with the load action of the actual state in terms of water permeability, considers the influence of normal stress and the thickness change caused by compression creep in the long-term service process on the vertical permeability coefficient, introduces the double indexes of gradient ratio and permeability coefficient ratio in terms of anti-blocking evaluation, and comprehensively evaluates the long-term blocking risk of the silt-geotextile system. According to the method for selecting the material of the reverse filter layer, firstly, candidate materials meeting the conditions are searched from a material database based on a filter layer matching algorithm, and then, the candidate materials are comprehensively optimized by combining with the clogging risk assessment, so that the optimal material of the reverse filter layer is determined. The design method provided by the invention effectively solves the problem that the geotextile reverse filtration layer design safety is insufficient under the condition of the silt geology in the existing method. In order to achieve the above purpose, the present invention provides the following technical solutions: a geotextile reverse filtration layer design method for enhancing the reverse filtration safety of silt comprises the following steps: The method comprises the steps of obtaining engineering silt parameters including silt characte