Construction method of yielding and resisting coupling type barrier for polluted site

Abstract

The invention belongs to the technical field of structures in polluted sites, and discloses a construction method of a yielding-resisting coupling type barrier for a polluted site, so as to meet the repair and safe development and utilization requirements of the polluted site and improve the dual effects of blocking pollutants and keeping a foundation pit stable. The construction method comprises the following steps: step 10, determining the spatial distribution of pollutants and the maximum depth of the pollutants, and determining a to-be-constructed area and a test point location of the barrier; step 20, testing permeability coefficients and compression moduli of in-situ soil layers at different depths in the to-be-constructed area of the barrier barrier; step 30, determining the cleaning and digging depth of the polluted soil in the cleaning and digging subareas and the test point positions of the polluted soil; 40, the foundation pit excavation depth of a building construction foundation pit excavation partition and a test point location is determined; 50, building parameters of the barrier barrier are obtained according to the contaminated soil excavation depth and the foundation pit excavation depth of the test point positions; and step 60, building the barrier according to the building parameters.

Description

Technical Field

[0001] The invention belongs to the field of construction of structures in contaminated sites, and in particular, relates to a method for constructing an anti-coupling type barrier in a contaminated site. Background Art

[0002] The development and utilization of contaminated sites provides valuable land resources for urban construction and renewal, but efficient and safe remediation of contaminated sites is a prerequisite for vacating land for use. Barrier barriers can effectively control the migration of pollutants or block the exposure pathways of pollutants, and are the most widely used technology in the remediation of contaminated sites. In addition, during the development and utilization of the remediated land, the construction of buildings often requires foundation pit excavation and the construction of underground facilities. Therefore, the barrier barriers used to block the migration of pollutants during the remediation of contaminated sites and the support barriers used to maintain the stability of the foundation pit structure during the site development process are planned in a coordinated manner, and barrier barriers that can meet the needs of the contaminated site remediation process and the site development process are constructed. This can effectively reduce the construction cost of the barrier barriers and increase the environmental friendliness of site remediation and safe utilization.

[0003] At present, the design parameters of contaminated site barriers mainly include the thickness, depth and material of the barriers. Due to the need to match the barrier construction equipment, the thickness of the barrier is usually 0.6 to 1.5 meters, and the permeability coefficient of the barrier material is less than 10. -6 cm / s or 10 -7 cm / s is appropriate. In addition, in order to simplify the design, the thickness and material of the barrier are often homogeneous along the depth direction of the barrier. However, in the process of contaminated site remediation, it is necessary to excavate the contaminated soil, and the development of the site after remediation requires excavation of foundation pits. Before the construction of contaminated site remediation, how to build a barrier that can have the dual functions of blocking pollutants and maintaining the stability of the foundation pit, and minimize the impact of the barrier on the stress state of the deep soil of the site, is a difficult problem faced by technical personnel in this field. Summary of the invention

[0004] The technical problem to be solved by the present invention is: in view of the shortcomings of the existing technology, a method for constructing an anti-coupling barrier for a contaminated site is provided to meet the needs of contaminated site remediation and safe development and utilization, enhance the dual functions of blocking pollutants and maintaining the stability of the foundation pit, and minimize the impact of the barrier on the stress state of the deep soil of the site.

[0005] In order to solve the above technical problems, the present invention adopts the following technical solutions: A method for constructing an anti-coupling barrier for a contaminated site comprises the following steps: Step 10: Conduct geotechnical engineering surveys on the contaminated site to determine the stratigraphic distribution of the proposed construction direction of the barrier; conduct soil contamination status surveys on the contaminated site to determine the spatial distribution of pollutants and the maximum depth of pollutants, and determine the proposed construction area and test points of the barrier; the barrier is constructed in sections, and the test points are located at the beginning and end of each section of the barrier; Step 20, conduct a static penetration test to test the permeability coefficient of the in-situ soil layer at different depths in the area where the barrier is to be constructed; conduct a flat shovel lateral expansion test to test the compression modulus of the in-situ soil layer at different depths in the area where the barrier is to be constructed; Step 30, according to the contaminated soil remediation plan of the contaminated site, determine the contaminated soil excavation zones and the contaminated soil excavation depths of the test points during the contaminated site remediation process; Step 40, according to the safe utilization plan for the contaminated site restoration, determine the excavation divisions of the construction pit and the excavation depths of the test points during the development of the contaminated site; Step 50, the barrier barrier comprises a first deformation resistance section, a second deformation resistance section and a free deformation section which are sequentially connected from top to bottom; according to the contaminated soil excavation depth of the test point determined in step 30 and the foundation pit excavation depth of the test point determined in step 40, the construction parameters of the barrier barrier are obtained; the construction parameters of the barrier barrier include the height of each section of the barrier barrier and the compression modulus of each section; Step 60 , constructing a barrier according to the construction parameters of the barrier obtained in step 50 .

[0006] As a preferred example, in step 40, the length of the construction pit excavation zone is equal to the length of the contaminated soil excavation zone, and the width of the construction pit excavation zone is equal to the width of the contaminated soil excavation zone.

[0007] As a preferred example, in step 50, the height of the first resistance deformation section of each barrier barrier is the arithmetic mean of the heights of the first resistance deformation section measured at the first and last test points of the barrier barrier; the height of the second resistance deformation section of each barrier barrier is the arithmetic mean of the heights of the second resistance deformation section measured at the first and last test points of the barrier barrier; the height of the free deformation section of each barrier barrier is the arithmetic mean of the heights of the free deformation section measured at the first and last test points of the barrier barrier; wherein the top buried depth of the first resistance deformation section at the test point is h 1T =0, bottom burial depth h 1B = h 2T ; The top burial depth of the second deformation resistance section at the test point h 2T =Min( H 1, H2)- h 0- h A , bottom burial depth h 2B =Max( H 1, H 2)+ h 0+ h A ;if h 2T <0, then let h 2T =0; if h 2B > h max , then let h 2B = h max ; The top burial depth of the free deformation section at the test point h 3T = h 2B , bottom burial depth h 3B = h max ; Where, Min( H 1, H 2) Indicates H 1 and H The minimum value of 2, H 1 indicates the depth of excavation of contaminated soil at the test point; H 2 indicates the excavation depth of the foundation pit at the test point; h 0 represents the tolerance height of the second deformation resistance segment; h A Represents the corrected height of the second deformation resistance segment; Max( H 1, H 2) Indicates H 1 and H The maximum value among 2; h max It represents the sum of the top burial depth of the aquiclude in the stratum and the depth of the barrier embedded in the aquiclude.

[0008] As a preferred example, the h 0The value range is 1 to 3 meters.

[0009] As a preferred example, the correction height of the second deformation resistance section is calculated according to formula (1): Formula (1) In the formula, a represents the coefficient related to the width of the barrier, dimensionless; wIndicates the width of the barrier, in meters; b It is the coefficient related to the permeability coefficient of the barrier and the permeability coefficient of the in-situ soil layer, in m; k c It represents the permeability coefficient of the barrier in cm / s; k s It represents the permeability coefficient of the in-situ soil layer, in cm / s.

[0010] As a preferred example, the a The value range is 0.3~0.8, w The value range is 0.6~1.2m, b The value range is 0.5~1.5m. k c For 10 -6 cm / s or 10 -7 cm / s; if the in-situ soil layer spans multiple soil layers, then k s The value is the permeability coefficient corresponding to the soil layer with the largest permeability coefficient.

[0011] As a preferred example, the compression modulus of the first deformation-resistant section is 2 to 4 times the average compression modulus of the in-situ soil layer within the depth range of the buried soil layer; the compression modulus of the second deformation-resistant section is 5 to 10 times the average compression modulus of the in-situ soil layer within the depth range of the buried soil layer.

[0012] As a preferred example, the compression modulus of the free deformation section is 90 to 110% of the average compression modulus of the in-situ soil layer within the depth range of the soil layer in which the free deformation section is buried.

[0013] As a preferred example, the step 60 specifically includes: constructing the barrier by sections, and the construction process of each barrier is as follows: step 601, filling the barrier filler into the formation according to the height and compression modulus of the free deformation section to form a free deformation section; step 602, filling the barrier filler above the free deformation section of the formation according to the height and compression modulus of the second resistance deformation section to form a second resistance deformation section; step 603, filling the barrier filler above the second resistance deformation section of the formation according to the height and compression modulus of the first resistance deformation section to form a first resistance deformation section, thereby building a barrier.

[0014] As a preferred example, in step 60, along the planned construction direction of the barrier, after one barrier is constructed, the next adjacent barrier is constructed.

[0015] Compared with the prior art, the method for constructing an anti-coupling barrier for a contaminated site of the present invention can enhance the dual functions of blocking pollutants and supporting foundation pits, and minimize the impact of the barrier on the stress state of the deep soil of the site. According to the depth of excavation of contaminated soil and the depth of excavation of foundation pits, the present invention divides the barrier into three sections in the vertical direction: a first resistance to deformation section, a second resistance to deformation section, and a free deformation section. The height of each section of the barrier and the compression modulus of each section are calculated respectively to obtain the construction parameters of each section of the barrier. The barrier constructed according to the construction parameters fully meets the structural stability during site remediation and redevelopment, and can reduce the impact of the barrier on the stress state of the deep soil of the site. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is a top view of a contaminated site in an embodiment of the present invention; Figure 2 is a cross-sectional view of soil strata in an embodiment of the present invention; Figure 3 yes Figure 1 A-A' section view; Figure 4 yes Figure 1 Middle B-B' section; Figure 5 yes Figure 1 C-C' section view.

[0017] In the figure: blocking barrier 1, first deformation resistance section 101, second deformation resistance section 102, free deformation section 103, fill layer 201, silty silty clay layer 202, silt sand and silty clay layer 203, silty clay and silt layer 204, excavation pit first partition 301, excavation pit second partition 302, first test point 401, second test point 402, third test point 403, first blocking barrier 501, second blocking barrier 502, contaminated soil 6, contaminated land boundary 7. DETAILED DESCRIPTION

[0018] The technical solution of the present invention is described in detail below. The test methods described in the following examples are conventional methods unless otherwise specified; the reagents and materials described are commercially available unless otherwise specified.

[0019] For sites where contaminated soil needs to be excavated during the remediation process and foundation pit excavation is required for site development and utilization after remediation, the roles played by barrier barriers in different depth ranges are not exactly the same. Therefore, the present invention proposes a coupling-type barrier barrier in combination with the different roles of barrier barriers at different depths in blocking pollutants and supporting foundation pits. Specifically, the coupling-type barrier barrier of the present invention sets different stiffnesses of barrier barriers in different depth ranges according to the functional requirements of barrier barriers during site remediation and development and utilization. The barrier barrier located above the groundwater level is the first resistance deformation section, and the compression modulus of the first resistance deformation section is 2 to 4 times the average compression modulus of the in-situ soil layer within the depth range of its buried soil layer. In this way, the first resistance deformation section can resist the deformation of the barrier barrier caused by stratum deformation during excavation and maintain structural stability. The barrier barrier located below the groundwater level and above the excavation depth of the foundation pit is the second resistance deformation section. The compression modulus of the second resistance deformation section is 5 to 10 times the average compression modulus of the in-situ soil layer within the depth range of its buried soil layer. The second deformation resistance section is used to resist the deterioration of the stiffness of the barrier under the action of the dry-wet cycle caused by the rise and fall of groundwater. The barrier below the excavation depth of the foundation pit is a free deformation section, and the compression modulus of the free deformation section is 90-110% of the average compression modulus of the in-situ soil layer within the depth range of its buried soil layer. The free deformation section ensures that the barrier does not significantly affect the stress-strain state of the deep soil after construction, and produces coordinated deformation with the in-situ soil layer, which can minimize the disturbance of the formation during the construction process. The barrier that meets the above characteristics is called an anti-coupling barrier.

[0020] A method for constructing an anti-coupling type barrier for a contaminated site according to an embodiment of the present invention comprises the following steps: Step 10, such as Figure 1 As shown, geotechnical engineering surveys are conducted on the contaminated site to determine the stratigraphic distribution of the proposed construction direction of the barrier; soil contamination status surveys are conducted on the contaminated site to determine the spatial distribution of pollutants and the maximum depth of pollutants, and to determine the proposed construction area and test points of the barrier; the barrier is constructed in sections, and the test points are arranged at the head and tail of each barrier. Two adjacent barrier sections share one test point. The test points are used to conduct static penetration tests and flat shovel lateral expansion tests.

[0021] Step 20: Conduct a static penetration test to test the permeability of the in-situ soil layer at different depths in the area where the barrier is to be constructed; conduct a flat shovel lateral expansion test to test the compression modulus of the in-situ soil layer at different depths in the area where the barrier is to be constructed.

[0022] Step 30, according to the contaminated soil remediation plan of the contaminated site, determine the contaminated soil excavation zones and the contaminated soil excavation depths of the test points during the contaminated site remediation process.

[0023] Step 40, according to the safe utilization plan for the contaminated site restoration, determine the excavation divisions of the construction pit and the excavation depths of the test points during the development of the contaminated site.

[0024] Step 50, the barrier comprises a first deformation resistance section 101, a second deformation resistance section 102 and a free deformation section 103 which are sequentially connected from top to bottom; according to the contaminated soil excavation depth of the test point determined in step 30 and the foundation pit excavation depth of the test point determined in step 40, the construction parameters of the barrier are obtained, and the construction parameters of the barrier include the height of each section of the barrier and the compression modulus of each section.

[0025] Step 60, obtaining the construction parameters of the barrier according to step 50, and constructing the barrier.

[0026] After the contaminated soil is excavated, the remediated soil or clean soil is backfilled; then the contaminated site is developed and the construction pit is excavated. Before these constructions are carried out, a barrier is built first.

[0027] The barrier constructed by the above method has different stiffness from top to bottom while meeting the permeability requirements. Figure 3 and Figure 4 As shown, the barrier barrier includes a first deformation resistance section 101, a second deformation resistance section 102 and a free deformation section 103. The stiffness of the barrier barrier is represented by the compression modulus. The first deformation resistance section 101, the second deformation resistance section 102 and the free deformation section 103 have different compression moduli. The function of the first deformation resistance section 101 is to support the foundation pit and resist the deformation and damage of the foundation pit caused by the excavation of contaminated soil or the excavation of the foundation pit. The function of the second deformation resistance section 102 is to resist the deformation and damage of the foundation pit under the alternating action of dry and wet cycles caused by the rise and fall of the groundwater level. The function of the free deformation section 103 is to produce a yielding deformation under the action of the in-situ soil stress during the soil excavation or the excavation of the foundation pit, and to produce a coordinated deformation with the in-situ soil. By designing the stiffness of the barrier barrier in sections, a barrier barrier that can simultaneously resist deformation and yield deformation under the stress of the in-situ soil layer is constructed, thereby reducing the cost of the barrier barrier and enhancing the environmental friendliness of the barrier barrier.

[0028] Preferably, in step 40, in order to simplify the design of the compression modulus of the barrier at different depths, the length of the construction pit excavation zone is equal to the length of the contaminated soil excavation zone, and the width of the construction pit excavation zone is equal to the width of the contaminated soil excavation zone.

[0029] Preferably, in step 50, the height of the first deformation resistance section 101 of each barrier barrier is the arithmetic mean of the heights of the first deformation resistance section 101 measured at the first and last test points of the barrier barrier. The height of the second deformation resistance section 102 of each barrier barrier is the arithmetic mean of the heights of the second deformation resistance section 102 measured at the first and last test points of the barrier barrier. The height of the free deformation section 103 of each barrier barrier is the arithmetic mean of the heights of the free deformation section 103 measured at the first and last test points of the barrier barrier. The top buried depth of the first deformation resistance section 101 at the test point is h 1T =0, bottom burial depth h 1B = h 2T ; The top burial depth of the second deformation resistance section 102 at the test point h 2T =Min( H 1, H 2)- h 0- h A , bottom burial depth h 2B =Max( H 1, H 2)+ h 0+ h A ;if h 2T <0, then let h 2T =0; if h 2B > h max , then let h 2B = h max ; The top burial depth of the free deformation section 103 at the test point h 3T = h 2B , bottom burial depth h 3B = h max Among them, Min( H 1, H 2) Indicates H 1 and H The minimum value of 2, H 1 indicates the depth of excavation of contaminated soil at the test point; H 2 indicates the excavation depth of the foundation pit at the test point; h 0 represents the tolerance height of the second deformation-resistant segment 102;h A represents the correction height of the second deformation resistance section 102; Max( H 1, H 2) Indicates H 1 and H The maximum value among 2; h max It represents the sum of the top buried depth of the aquiclude in the stratum and the depth of the barrier embedded in the aquiclude. Preferably, the depth of the barrier embedded in the aquiclude is 1.0 to 2.0 m. Preferably, h 0The value range is 1 to 3 meters.

[0030] Preferably, h A It is related to the width and permeability of the barrier and the permeability of the in-situ soil layer.

[0031] Correction height of the second deformation resistance section 102 h A , calculated according to formula (1): Formula (1) In the formula, a represents the coefficient related to the width of the barrier, dimensionless; w Indicates the width of the barrier, in meters; b It is the coefficient related to the permeability coefficient of the barrier and the permeability coefficient of the in-situ soil layer, in m; k c It represents the permeability coefficient of the barrier in cm / s; k s represents the permeability coefficient of the in-situ soil layer, in cm / s. Preferably, a The value range is 0.3~0.8, w The value range is 0.6~1.2m, b The value range is 0.5~1.5. k c For 10 -6 cm / s or 10 -7 cm / s; if the in-situ soil layer spans multiple soil layers, then k s The value is the permeability coefficient corresponding to the soil layer with the largest permeability coefficient.

[0032] The height correction of the second deformation resistance section 102 is determined by the width of the barrier and the ratio of the permeability coefficient of the in-situ soil layer to the permeability coefficient of the barrier. h ARefined calculations can effectively consider the impact of changes in the foundation pit dewatering curve on the moisture content of the barrier, thereby incorporating the degradation process of the service performance of the barrier under the action of dry-wet cycles into the design of the barrier height.

[0033] Preferably, the compression modulus of the first deformation resistance section 101 is 2 to 4 times the average compression modulus of the in-situ soil layer within the depth range of the buried soil layer. The stiffness of this section of the barrier is within this range, which can resist the deformation of the barrier caused by the deformation of the stratum during the excavation process and maintain the stability of the structure. The compression modulus of the second deformation resistance section 102 is 5 to 10 times the average compression modulus of the in-situ soil layer within the depth range of the buried soil layer. For the barrier located below the groundwater level and above the site excavation depth, it is necessary to have a greater stiffness than the first deformation resistance section 101 to resist the deterioration of the stiffness of the barrier under the dry-wet cycle caused by the rise and fall of groundwater. The compression modulus of the free deformation section 103 is 90 to 110% of the average compression modulus of the in-situ soil layer within the depth range of the buried soil layer. The stiffness of this section of the barrier is designed to be close to the stiffness of the soil of the original stratum, ensuring that the stress-strain state of the deep soil is not significantly affected after the construction of this section of the barrier, and the synergistic deformation is produced with the in-situ soil layer, so as to minimize the disturbance of the stratum during the construction process. In this preferred example, the compression modulus of the second deformation resistance section 102 is greater than that of the first deformation resistance section 101, and the compression modulus of the first deformation resistance section 101 is greater than that of the free deformation section 103. For sites that require excavation of contaminated soil during the remediation process and excavation of foundation pits for site development and utilization after remediation, the roles played by barriers in different depth ranges are not exactly the same. The stiffness of the barrier barrier is designed in sections according to its burial depth, which can give full play to the supporting role of the barrier barrier on the excavated foundation pit and maintain the stability of the foundation pit. By optimizing the stiffness of the barrier barrier, the amount of barrier barrier material used can be effectively reduced. At the same time, the selection of deep barrier barriers can produce concession deformation with the original stratum deformation, effectively reducing the impact of the barrier barrier on the stratum stress environment, and making the construction activities more adaptable to the natural environment.

[0034] Preferably, Figure 5 As shown, step 60 specifically includes: constructing the barrier by piece, and the construction process of each barrier is as follows: Step 601 , according to the height and compression modulus of the free deformation section 103 , fill the barrier filler into the formation to form the free deformation section 103 .

[0035] Step 602 , according to the height and compression modulus of the second deformation-resistant segment 102 , a blocking barrier filler is filled above the free deformation segment 103 of the formation to form the second deformation-resistant segment 102 .

[0036] Step 603, according to the height and compression modulus of the first deformation resistance segment 101, a barrier filler is filled above the second deformation resistance segment 102 of the formation to form the first deformation resistance segment 101, thereby building a barrier.

[0037] In the above method for constructing the barrier, the free deformation section 103, the second deformation resistance section 102, and the first deformation resistance section 101 have different heights and compression moduli. This can fully meet the stability of the foundation pit structure during site restoration and redevelopment, and can reduce the structural damage to the original stratum caused by the construction of the barrier.

[0038] Preferably, in step 60, after one barrier is constructed, the next adjacent barrier is constructed along the planned construction direction of the barrier until the construction is completed.

[0039] During the remediation of contaminated sites, the barrier barrier has the functions of blocking pollutants and supporting the foundation pit. The barrier barrier has a certain rigidity. During the excavation of contaminated soil, the barrier barrier is maintained without significant deformation, and the foundation pit structure is maintained stable. Similarly, the barrier barrier can maintain the stability of the foundation pit structure during site development. Usually, the excavation depth of the contaminated site soil and the excavation depth of the site development foundation pit are not the same, and the depths of the two directly determine the rigidity design requirements of the barrier barrier. The greater the rigidity of the barrier barrier, the greater the amount of barrier barrier material that needs to be added, thereby increasing the construction cost. The present invention can effectively reduce the amount of barrier barrier material used by optimizing the rigidity design of the barrier barrier; at the same time, the deep barrier barrier can produce a yielding deformation with the deformation of the original stratum, effectively reducing the impact of the barrier barrier on the stratum stress environment, so that the construction activities are more adapted to the natural environment.

[0040] The barrier barrier is divided into a first deformation resistance section 101, a second deformation resistance section 102, and a free deformation section 103 from top to bottom according to the depth of the buried stratum. During the excavation of contaminated soil for the restoration of the contaminated site and the excavation of the foundation pit for the safe development and utilization of the site after restoration, the first deformation resistance section 101 and the second deformation resistance section 102 of the barrier barrier can effectively resist the deformation of the barrier barrier caused by external disturbances and maintain structural stability; while the free deformation section 103 produces cooperative deformation with the in-situ soil and maintains the anti-seepage and pollution interception performance of the barrier barrier. The barrier barrier can effectively reduce the use of barrier barrier materials, reduce construction costs, and increase the environmental friendliness of the barrier barrier.

[0041] Examples and comparative examples are provided below.

[0042] Example With reference to the previous investigation data of the contaminated site and the risk control plan for the contaminated site, it is necessary to build a barrier 1 at the boundary 7 of the contaminated plot to separate the contaminated soil 6 from the surrounding clean soil. The length of the barrier 1 is 120m.

[0043] Conduct geotechnical investigation of the contaminated site to determine the distribution of strata in the direction of the proposed construction of the barrier. Figure 2 As shown, the strata along which the barrier is to be constructed are, from top to bottom, a fill layer 201, a silty clay layer 202, a silty clay layer 203, and a silty clay layer 204. Among them, the silty clay layer 204 is equivalent to an impermeable layer, and the silty clay layer 202 and the silty clay layer 203 are equivalent to non-impermeable layers.

[0044] A soil pollution survey was conducted at the contaminated site. The maximum soil pollution depth was 7.5m. Part of the silt sand and silty clay layer 203 was already polluted. The contaminated soil was excavated out of the site by excavation. Therefore, the excavation depth was H 1 is 7.5 m. Considering that the restoration process may cause groundwater pollution to the silty sand and silty clay layer 203, the barrier is embedded in the silty clay and silty soil layer 204 (aquiclude).

[0045] According to the safe reuse plan for the remediation of contaminated sites, the construction pit was excavated in two areas during the site redevelopment process. The excavation depth of the first excavation pit 301 was 9.0m, and the excavation depth of the second excavation pit 302 was 4.5m. The length of the two partitions along the direction of the barrier is 60m, and the width perpendicular to the barrier is 120m, so the barrier was divided into two sections for design and construction.

[0046] The length of the contaminated soil excavation zone during the remediation of the contaminated site is equal to the length of the construction pit excavation zone, and the width of the contaminated soil excavation zone is equal to the width of the construction pit excavation zone.

[0047] Along the proposed construction direction of the barrier, three test points are arranged at equal intervals, namely the first test point 401, the second test point 402, and the third test point 403. For each test point, the static penetration test and the flat shovel lateral expansion test are used to test the permeability coefficient and compression modulus of each soil layer; at the same time, the elevation of the top and bottom surfaces of each soil layer is recorded. Since there are slight differences in the permeability coefficient and compression modulus of soil at different depths in the same soil layer, on the test curves of the static penetration test and the flat shovel lateral expansion test, the test data are selected at intervals of 1m, and the average value of the collected data at each interval position is calculated as the soil permeability coefficient and compression modulus of the soil layer. The relative elevation of the top surface, relative elevation of the bottom surface, permeability coefficient and compression modulus of the three test points obtained by the test are shown in Tables 1 to 3.

[0048] Table 1 The first test point information table

[0049] Table 2 Second test point information table

[0050] Table 3 The third test point information table

[0051] 1. Calculate the heights of the first deformation-resistant section 101 , the second deformation-resistant section 102 and the free deformation section 103 of the barrier.

[0052] (1) If Figure 3 As shown, at the first test point 401, H 1=7.5m, H 2=9.0m, then Min( H 1, H 2)=7.5m, Max( H 1, H 2) = 9.0m; h 0 represents the tolerance height of the second deformation resistance section 102, and in this embodiment, the value is 1.5m. In this embodiment, the width of the barrier 1 is w The value is 0.8m. a The value is 0.5; the permeability coefficient of barrier 1 k c The value is 10 - 6 cm / s. Since the second deformation resistance section 102 must pass through the silt sand and silty clay layer 203 (the soil layer where the confined water is located), it tends to be conservative. k s The permeability coefficient of the silt sand and silty clay layer 203 is taken as 3.95×10 -4 cm / s); b The value is 1.0m, so the correction height is calculated according to formula (1): h A =0.5×0.8+1×log(3.95×10 -4 ÷10 -6 ) =3.0m. The top elevation of the silty clay and silt layer 204 at this point is 19.6m, and the depth of the barrier 1 embedded in the silty clay and silt layer 204 is 1.4m. Therefore, h max It is 21.0m.

[0053] It is calculated that at the first test point 401, the top buried depth of the first deformation resistance section 101 in the barrier 1 is h 1T =0, bottom burial depth h 1B=7.5-1.5-3.0=3.0m; top burial depth of the second deformation resistance section 102 h 2T =3.0m, bottom burial depth h 2B =9.0+1.5+3.0=13.5m; top burial depth of free deformation section 103 h 3T =13.5m, bottom burial depth h 3B =21.0m.

[0054] (2) During the site redevelopment process, the second test point 402 is the boundary between two areas of the construction pit, and the excavation depth of the first partition 301 of the excavation pit is 9.0 m. Figure 3 As shown; the excavation depth of the second partition 302 of the foundation pit is 4.5m, as Figure 4 Therefore, the height of each section of the barrier is calculated according to the excavation depth of the two partitions.

[0055] First, the calculation is performed based on the second test point 402 being in the first partition 301 of the excavation pit: like Figure 3 As shown, at the second test point 402, H 1=7.5m, H 2=9.0m, then Min( H 1, H 2)=7.5m, Max( H 1, H 2) = 9.0m; h 0 is the tolerance height of the second deformation resistance section 102, which is 1.5 m. In this embodiment, the width of the barrier 1 is w The value is 0.8m. a The value is 0.5. The permeability coefficient of barrier 1 k c The value is 10 -6 cm / s. Since the second deformation resistance section 102 must pass through the silt sand and silty clay layer 203 (the soil layer where the confined water is located), it tends to be conservative. k s The permeability coefficient of the silt sand and silty clay layer 203 is 3.56×10 -4 cm / s. b The value is 1.0m. Calculate the correction height according to formula (1): h A The value is 0.5×0.8+1×log(3.56×10 -4 ÷10 -6) =2.95m. The top elevation of the silty clay and silt layer 204 at the test point is 20.3m, and the depth of the barrier 1 embedded in the silty clay and silt layer 204 is 1.4m. Therefore, h max It is 21.7m.

[0056] The calculation shows that the second test point 402 is located at the top buried depth of the first deformation resistance section 101 of the barrier 1 of the first partition 301 of the excavation pit. h 1T =0, bottom burial depth h 1B =7.5-1.5-2.95=3.05m; top burial depth of the second deformation resistance section 102 h 2T =3.05m, bottom burial depth h 2B =9.0+1.5+2.95=13.45m; top burial depth of free deformation section 103 h 3T =13.45m, bottom burial depth h 3B =21.7m.

[0057] Then, the calculation is performed based on the second test point 402 being in the second partition 302 of the excavated foundation pit: like Figure 4 As shown, at the second test point 402, H 1=7.5m, H 2=4.5m, then Min( H 1, H 2)=4.5m, Max( H 1, H 2) = 7.5m; h 0 is the tolerance height of the second deformation resistance section 102 of the barrier 1, and its value is 1.5m. In this embodiment, the width of the barrier 1 is w The value is 0.8m. a The value is 0.5. The permeability coefficient of barrier 1 k c The value is 10 -6 cm / s. Since the second deformation resistance section 102 must pass through the silt sand and silty clay layer 203 (the soil layer where the confined water is located), it tends to be conservative. k s The permeability coefficient of silt sand and silty clay is 3.56×10 -4 cm / s; b The value is 1.0. Calculate the correction height according to formula (1): h A=0.5×0.8+1×log(3.56×10 -4 ÷10 -6 ) =2.95m. The top elevation of the silty clay and silt layer 204 at the second test point is 20.3m, and the depth of the barrier 1 embedded in the silty clay and silt layer 204 is 1.4m. h max It is 21.7m.

[0058] The calculation shows that the second test point 402 is located at the top buried depth of the first deformation resistance section 101 of the barrier 1 of the second partition 302 of the excavation pit. h 1T =0, bottom burial depth h 1B =4.5-1.5-2.95=0.05m; top burial depth of the second deformation resistance section 102 h 2T =0.05m, bottom burial depth h 2B =7.5+1.5+2.95=11.95m; top burial depth of free deformation section 103 h 3T =11.95m, bottom burial depth h 3B =21.7m.

[0059] (3) The heights of each section of the barrier 1 at the third test point 403.

[0060] like Figure 4 As shown, at the third test point 403, H 1=7.5m, H 2=4.5m, then Min( H 1, H 2)=4.5m, Max( H 1, H 2) = 7.5m; h 0 is the tolerance height of the second deformation resistance section 102, which is 1.5 m. In this embodiment, the width of the barrier 1 is w The value is 0.8m. a The value is 0.5; the permeability coefficient of barrier 1 k c The value is 10 -6 cm / s. Since the second deformation resistance section 102 must pass through the silt sand and silty clay layer 203 (the soil layer where the confined water is located), it tends to be conservative. k s The permeability coefficient of the silt sand and silty clay layer 203 is 3.47×10 -4 cm / s; bThe value is 1.0. Calculate the correction height according to formula (1): h A =0.5×0.8+1×log(3.47×10 -4 ÷10 -6 ) = 2.94m. The top elevation of the silty clay and silt layer at the test point is 21.7m, and the embedding depth of the barrier is 1.4m. h max It is 23.1m.

[0061] It is calculated that at the third test point 403, the top buried depth of the first deformation resistance section 101 of the barrier 1 is h 1T =0, bottom burial depth h 1B =4.5-1.5-2.94=0.06m; top burial depth of the second deformation resistance section 102 h 2T =0.06m, bottom burial depth h 2B =7.5+1.5+2.94=11.94m; top burial depth of free deformation section 103 h 3T =11.94m, bottom burial depth h 3B =23.1m.

[0062] (ii) Calculating the compression modulus of the first deformation resistance section 101 , the second deformation resistance section 102 , and the free deformation section 103 of the barrier 1 .

[0063] (1) The top burial depth of the first anti-deformation section 101 at the first test point 401 h 1T =0, bottom burial depth h 1B =3.0m; top burial depth of the second deformation resistance section 102 h 2T =3.0m, bottom burial depth h 2B =13.5m; top burial depth of free deformation section 103 h 3T =13.5m, bottom burial depth h 3B =21.0m. Therefore, according to the top surface relative elevation, bottom surface relative elevation and compression modulus in Table 1, the compression modulus of each section of the barrier 1 is calculated.

[0064] If a certain section of the barrier 1 spans over more than two soil layers, the average compression modulus of the spanning soil layers is weighted by the thickness of the spanning soil layers, and the average compression modulus is used as the compression modulus of the spanning soil layers of the section.

[0065] Calculate the compression modulus of the soil layer within the buried depth range of the first deformation resistance section 101 at the first test point 401: The first deformation resistance section 101 at the first test point 401 is buried 3.0m deep, spanning the fill layer 201 (spanning thickness of 1.3m) and the silty silty clay layer 202 (spanning thickness of 1.7m), and through the flat shovel lateral expansion test, the compression modulus of the fill layer 201 is 12.7MPa, and the compression modulus of the silty silty clay layer 202 is 9.5MPa. The weighted calculation of the average compression modulus of the soil layer spanned by the first deformation resistance section 101 is 12.7×1.3÷3.0+9.5×1.7÷3.0=10.89MPa.

[0066] Calculate the average compression modulus of the soil layer within the buried depth range of the second deformation resistance section 102 at the first test point 401: The second deformation resistance section 102 at the first test point 401 is buried at a depth of 10.5m, spanning the silty clay layer 202 (spanning thickness of 1.5m) and the silty clay layer 203 (spanning thickness of 9.0m), and through the flat shovel lateral expansion test, the compression modulus of the silty clay layer 202 is 9.5MPa, and the compression modulus of the silty clay layer is 23.5MPa. The weighted calculation of the average compression modulus of the soil layer spanned by the second deformation resistance section 102 is 9.5×1.5÷10.5+23.5×9.0÷10.5=21.50MPa.

[0067] Calculate the compression modulus of the soil layer within the burial depth range of the free deformation section 103 at the first test point 401: The burial depth of the free deformation section 103 at the first test point 401 is 7.5m, spanning the silt sand and silty clay layer 203 (spanning thickness is 6.1m) and the silty clay and silty soil layer 204 (spanning thickness is 1.4m), and through the flat shovel lateral expansion test, the compression modulus of the silt sand and silty clay layer is 23.5MPa, and the compression modulus of the silty clay and silty soil layer is 12.3MPa. The weighted calculation of the average compression modulus of the soil layer spanned by the free deformation section 103 is 23.5×6.1÷7.5+12.3×1.4÷7.5=21.41MPa.

[0068] Taking into account the stability and construction cost of the barrier, in this embodiment, the compression modulus of the first deformation-resistant section 101 is 3 times the average compression modulus of the in-situ soil layer within the depth range of its burial layer, the compression modulus of the second deformation-resistant section 102 is 5 times the average compression modulus of the in-situ soil layer within the depth range of its burial layer, and the compression modulus of the barrier barrier of the free deformation section 103 is designed to be 90% of the average compression modulus of the in-situ soil layer within the depth range of its burial layer.

[0069] Therefore, at the first test point 401 , the compression modulus of the first anti-deformation section 101 is 32.67 MPa, the compression modulus of the second anti-deformation section 102 is 107.50 MPa, and the compression modulus of the free deformation section 103 is 19.27 MPa.

[0070] (2) Because the second test point 402 is the boundary between two areas of the construction pit during the site redevelopment process, the excavation depth of the first partition 301 of the excavation pit is 9.0 m, and the excavation depth of the second partition 302 of the excavation pit is 4.5 m. Therefore, the compression modulus of each section of the barrier is calculated according to the excavation depth of the two partitions.

[0071] First, the calculation is performed based on the second test point 402 being in the first partition 301 of the excavation pit: At the second test point 402, the top buried depth of the first anti-deformation section 101 is h 1T =0, bottom burial depth h 1B =3.05m; top burial depth of the second deformation resistance section 102 h 2T =3.05m, bottom burial depth h 2B =13.45m; top burial depth of free deformation sub-segment 103 h 3T =13.45m, bottom burial depth h 3B = 21.7m. According to the top relative elevation, bottom relative elevation and compression modulus in Table 2, calculate the compression modulus of each section of the barrier.

[0072] The first deformation resistance section 101 at the second test point 402 is buried 3.05m deep, spanning the fill layer 201 (spanning thickness of 1.6m) and the silty silty clay layer 202 (spanning thickness of 1.45m), and through the flat shovel lateral expansion test, the compression modulus of the fill layer 201 is 11.8MPa, and the compression modulus of the silty silty clay layer 202 is 6.7MPa. The weighted calculation of the average compression modulus of the soil layer spanned by the first deformation resistance section 101 is 11.8×1.6÷3.05+6.7×1.45÷3.05=9.38MPa.

[0073] The second deformation resistance section 102 at the second test point 402 is buried at a depth of 10.4m, spanning the silty clay layer 202 (spanning thickness of 1.85m) and the silty clay layer 203 (spanning thickness of 8.55m), and through the flat shovel lateral expansion test, the compression modulus of the silty clay layer 202 is 6.7MPa, and the compression modulus of the silty clay layer is 21.0MPa. The average compression modulus of the soil layer spanned by the second deformation resistance section 102 is 6.7×1.85÷10.4+21.0×8.55÷10.4=18.46MPa.

[0074] The free deformation section 103 at the second test point 402 has a burial depth of 8.25m, spanning the silty sand and silty clay layer 203 (spanning thickness of 6.85m) and the silty clay and silty soil layer 204 (spanning thickness of 1.4m), and through the flat shovel lateral expansion test, the compression modulus of the silty sand and silty clay layer is 21.0MPa, and the compression modulus of the silty clay and silty soil layer is 11.8MPa. The weighted calculation of the average compression modulus of the soil layer spanned by the free deformation section 103 is 21.0×6.85÷8.25+11.8×1.4÷8.25=19.44MPa.

[0075] In this embodiment, the compression modulus of the first deformation resistance section 101 is 2 times the average compression modulus of the in-situ soil layer within the depth range of the buried soil layer; the compression modulus of the second deformation resistance section 102 is 7 times the average compression modulus of the in-situ soil layer within the depth range of the buried soil layer; the compression modulus of the free deformation section 103 is 100% of the average compression modulus of the in-situ soil layer within the depth range of the buried soil layer, that is, the same as the average compression modulus of the in-situ soil layer. Therefore, the compression modulus of the first deformation resistance section 101 at the second test point 402 in the first partition 301 of the excavated foundation pit is 18.76MPa, the compression modulus of the second deformation resistance section 102 is 129.22MPa, and the compression modulus of the free deformation section 103 is 19.44MPa.

[0076] Then, the calculation is performed based on the second test point 402 being in the second partition 302 of the excavated foundation pit: At the second test point 402, the top buried depth of the first anti-deformation section 101 is h 1T =0, bottom burial depth h 1B =0.05m; top burial depth of the second deformation resistance section 102 h 2T =0.05m, bottom burial depth h 2B =11.95m; top burial depth of free deformation section 103 h 3T =11.95m, bottom burial depthh 3B =21.7m. According to the top relative elevation, bottom relative elevation and compression modulus of the second test point in Table 2, the compression modulus of each section of the barrier is calculated.

[0077] At the second test point 402, the first deformation resistance section 101 did not cross the first soil layer, so its compression modulus was 11.80 MPa.

[0078] The second deformation resistance section 102 at the second test point 402 is buried at a depth of 11.9m, spanning the fill layer 201 (spanning thickness of 1.55m), the silty clay layer 202 (spanning thickness of 3.30m) and the silty clay layer 203 (spanning thickness of 7.05m), and through the flat shovel lateral expansion test, the compression modulus of the fill layer 201 is 11.8MPa, the compression modulus of the silty clay layer 202 is 6.7MPa, and the compression modulus of the silty clay layer is 21.0MPa. The average compression modulus of the soil layer spanned by the second deformation resistance section 102 is weighted calculated to be 11.8×1.55÷11.9+6.7×3.30÷11.9+21.0×7.05÷11.9=15.84MPa.

[0079] The free deformation section 103 at the second test point 402 has a burial depth of 9.75m, spanning the silty sand and silty clay layer 203 (spanning thickness of 8.35m) and the silty clay and silty soil layer 204 (spanning thickness of 1.4m), and through the flat shovel lateral expansion test, the compression modulus of the silty sand and silty clay layer is 21.0MPa, and the compression modulus of the silty clay and silty soil layer is 11.8MPa. The weighted calculation of the average compression modulus of the soil layer spanned by the free deformation section 103 is 21.0×8.35÷9.75+11.8×1.4÷9.75=19.68MPa.

[0080] In this embodiment, the compression modulus of the first deformation-resistant section 101 is 4 times the average compression modulus of the in-situ soil layer within the depth range of the buried soil layer, the compression modulus of the second deformation-resistant section 102 is 10 times the average compression modulus of the in-situ soil layer within the depth range of the buried soil layer, and the compression modulus of the free deformation section 103 is 110% of the average compression modulus of the in-situ soil layer within the depth range of the buried soil layer.

[0081] Therefore, the compression modulus of the first resistance deformation section 101 at the second test point 402 in the second partition 302 of the excavated foundation pit is 47.20 MPa, the compression modulus of the second resistance deformation section 102 is 158.4 MPa, and the compression modulus of the free deformation section 103 is 21.65 MPa.

[0082] (3) The top buried depth of the first anti-deformation section 101 at the third test point 403 h1T =0, bottom burial depth h 1B =0.06m; top burial depth of the second deformation resistance section 102 h 2T =0.06m, bottom burial depth h 2B =11.94m; top burial depth of free deformation section 103 h 3T =11.94m, bottom burial depth h 3B =23.1m. Therefore, according to the top relative elevation, bottom relative elevation and compression modulus in Table 3, the compression modulus of each section of the barrier is calculated.

[0083] The first deformation resistance section 101 at the third test point 403 does not cross the first soil layer, and the compression modulus is 10.5 MPa.

[0084] The second deformation resistance section 102 at the third test point 403 is buried at a depth of 11.88m, spanning the fill layer 201 (spanning thickness of 1.44m), the silty silty clay layer 202 (spanning thickness of 4.00m) and the silty sand and silty clay layer 203 (spanning thickness of 6.44m), and through the flat shovel lateral expansion test, the compression modulus of the fill layer 201 is 10.5MPa, the compression modulus of the silty silty clay layer 202 is 8.3MPa, and the compression modulus of the silty sand and silty clay layer is 22.3MPa. The weighted calculation of the average compression modulus of the soil layer spanned by the second deformation resistance section 102 is 10.5×1.44÷11.88+8.3×4.0÷11.88+22.3×6.44÷11.88=16.16MPa.

[0085] The free deformation section 103 at the third test point 403 has a burial depth of 11.16m, spanning the silty sand and silty clay layer 203 (spanning thickness of 9.76m) and the silty clay and silty soil layer 204 (spanning thickness of 1.4m), and through the flat shovel lateral expansion test, the compression modulus of the silty sand and silty clay layer is 22.3MPa, and the compression modulus of the silty clay and silty soil layer is 15.7MPa. The weighted calculation of the average compression modulus of the soil layer spanned by the free deformation section 103 is 22.3×9.76÷11.16+15.7×1.4÷11.16=21.47MPa.

[0086] In this embodiment, the compression modulus of the first deformation resistance section 101 is 3 times the average compression modulus of the in-situ soil layer within the depth range of the buried soil layer, the compression modulus of the second deformation resistance section 102 is 8 times the average compression modulus of the in-situ soil layer within the depth range of the buried soil layer, and the compression modulus of the free deformation section 103 is 100% of the average compression modulus of the in-situ soil layer within the depth range of the buried soil layer. Therefore, at the third test point, the compression modulus of the first deformation resistance section 101 is 31.50MPa, the compression modulus of the second deformation resistance section 102 is 129.28MPa, and the compression modulus of the free deformation section 103 is 21.47MPa. After calculation and design, the construction parameters of each end point of the barrier 1 are shown in Table 4.

[0087] Table 4

[0088] 3. Design of construction parameters for each barrier The construction parameters of each barrier barrier are the arithmetic mean of the construction parameters of the first and last endpoints, as shown in Table 5. The data in Table 5 are retained to two decimal places. The construction parameters of the first barrier barrier are calculated using the data of the first test point and the second test point located in the first partition of the excavation pit. The construction parameters of the second barrier barrier are calculated using the data of the second test point and the third test point located in the second partition of the excavation pit. For example, the bottom burial depth of the first resistance deformation section 101 corresponding to the first test point 401 is 3.0m, and the bottom burial depth of the first resistance deformation section 101 of the first partition 301 of the excavation pit of the second test point 402 is 3.05m, then the bottom burial depth of the first resistance deformation section 101 of the first barrier barrier 501 is 0.5×(3.00+3.05)=3.03m. For example, the compression modulus of the first resistance to deformation section 101 corresponding to the first test point 401 is 32.67 MPa, and the compression modulus of the first resistance to deformation section 101 corresponding to the first partition 302 of the excavation pit at the second test point 402 is 18.76 MPa. Then, the compression modulus of the first resistance to deformation section 101 of the first barrier is 0.5×(32.67+18.76)=25.72 m.

[0089] Table 5 Construction parameters of each barrier

[0090] 4. In-situ soil improvement materials and dosage design In-situ soil is collected to conduct a test on the dosage optimization of the barrier construction material. In this embodiment, the compression modulus requirement of the free deformation section 103 is relatively low, and bentonite is used to improve the in-situ soil. According to experience, the dosage is 6% of the dry weight of the in-situ soil.

[0091] The first deformation resistance section 101 and the second deformation resistance section 102 require that the barrier construction material has a large compression modulus. In this embodiment, cement activated bentonite is used to improve the in-situ soil. D (Unit: %) Based on the compression modulus of the barrier E (Unit: MPa) Design requirements are determined and the calculation method is: D =2+ β × E In the formula, β It is the empirical coefficient, the value is 0.2, and the unit is MPa -1 In order to facilitate construction, the dosage D For example, the compression modulus of the first deformation-resistant segment 101 in the first barrier 501 is 25.72 MPa, and the dosage is D =2+0.2×25.72=7.14%, rounded up to 8%. For another example, the compression modulus of the second deformation-resistant segment 102 in the second barrier 502 is 143.84 MPa, and the dosage is D 2+0.2×143.84=30.77%, rounded up to 31%. According to the data in Table 5 and the above formula, calculate the dosage of each section of each barrier.

[0092] Table 6 Dosage of in-situ soil improvement materials

[0093] 5. Construction of barrier According to the dosage of the in-situ soil improvement material in Table 6, the barrier is constructed by the double-axis mixing method. The soil improvement material is added in corresponding mass proportions to different sections of each barrier, and the construction of the first barrier 501 and the second barrier 502 is completed in turn.

[0094] According to the barrier construction method of the present invention, the in-situ soil improvement materials required to construct a 120m barrier are calculated. The calculation process is shown in Table 7. The dry density of the soil layer corresponding to the first deformation resistance section 101 and the free deformation section 103 is 1.6g / cm 3 The dry density of the soil layer corresponding to the second deformation resistance section 102 is 1.7 g / cm 3. The calculation process of the mass of modified materials in each section of each barrier is: the length of the section × the width of the section × the thickness of the stratum corresponding to the section × the dry density of the soil × the amount of cement-activated bentonite (bentonite). In this embodiment, the length of each section is 60 meters and the width is 0.8 meters. For example, the mass of cement-activated bentonite in the first deformation-resistant section 101 of the first barrier 501 is 60×0.8×3.03×1.6×8%=18.62t. For another example, the mass of bentonite in the free deformation section of the first barrier 501 is 60×0.8×7.87×1.6×6%=36.26t. According to Table 7, the amount of cement-activated bentonite is calculated to be 18.62+221.71+0.46+300.77=541.56t, and the amount of bentonite is 36.26+48.15=84.41t.

[0095] Table 7 Amount of improved materials

[0096] Comparative Example The traditional barrier design method is adopted, the stiffness of the barrier is considered, and the stiffness of the barrier in all depth ranges is set to be the same as the second deformation resistance section of the second barrier 502. Cement-activated bentonite is selected as the modified material of the in-situ soil, and the corresponding cement-activated bentonite content is 31% (see Table 6). The barrier is not constructed in sections. The parameters of the entire barrier are the same. The length of the entire barrier is 120m and the width is 0.8m. The depth of the barrier is calculated based on embedding 1.5m into the silty clay and silt layer. The average burial depth of the top surface of the silty clay and silt layer at the first test point 401, the second test point 402, and the third test point 403 is 20.53m, so the depth of the barrier is 22.03m. Let the dry density of the soil layer be 1.6g / cm 3 The calculated amount of cement-activated bentonite is 120×0.8×22.03×1.6×31%=1048.98t.

[0097] By comparison, it can be seen that the amount of improved material used in this embodiment can save about 1-(541.56+84.41) / 1048.98×100%=40.33%.

[0098] The basic principles, main features and advantages of the present invention are shown and described above. Those skilled in the art should understand that the present invention is not limited to the above specific embodiments, and the descriptions in the above specific embodiments and the specification are only for further illustrating the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, and these changes and improvements all fall within the scope of the present invention claimed for protection.

Claims

1. A method for constructing an anti-coupling barrier at a contaminated site, characterized in that: The method comprises the following steps: Step 10: Conduct geotechnical engineering surveys on the contaminated site to determine the stratigraphic distribution of the proposed construction direction of the barrier; conduct soil contamination status surveys on the contaminated site to determine the spatial distribution of pollutants and the maximum depth of pollutants, and determine the proposed construction area and test points of the barrier; the barrier is constructed in sections, and the test points are located at the beginning and end of each section of the barrier; Step 20, conduct a static penetration test to test the permeability coefficient of the in-situ soil layer at different depths in the area where the barrier is to be constructed; conduct a flat shovel lateral expansion test to test the compression modulus of the in-situ soil layer at different depths in the area where the barrier is to be constructed; Step 30, according to the contaminated soil remediation plan of the contaminated site, determine the contaminated soil excavation zones and the contaminated soil excavation depths of the test points during the contaminated site remediation process; Step 40, according to the safe utilization plan for the contaminated site restoration, determine the excavation divisions of the construction pit and the excavation depths of the test points during the development of the contaminated site; Step 50, the barrier comprises a first deformation resistance section (101), a second deformation resistance section (102) and a free deformation section (103) which are sequentially connected from top to bottom; according to the contaminated soil excavation depth of the test point determined in step 30 and the foundation pit excavation depth of the test point determined in step 40, the construction parameters of the barrier are obtained; the construction parameters of the barrier include the height of each section of the barrier and the compression modulus of each section; Step 60 , constructing a barrier according to the construction parameters of the barrier obtained in step 50 .

2. The method for constructing an anti-coupling type barrier for a contaminated site according to claim 1, characterized in that: In step 40, the length of the construction pit excavation zone is equal to the length of the contaminated soil excavation zone, and the width of the construction pit excavation zone is equal to the width of the contaminated soil excavation zone.

3. The method for constructing an anti-coupling type barrier for a contaminated site according to claim 1, characterized in that: In step 50, the height of the first deformation resistance section (101) of each barrier barrier is the arithmetic average of the heights of the first deformation resistance section (101) measured at the first and last test points of the barrier barrier; The height of the second deformation resistance section (102) of each barrier barrier is the arithmetic average of the heights of the second deformation resistance section (102) measured at the first and last test points of the barrier barrier; The height of the free deformation section (103) of each barrier is the arithmetic average of the heights of the free deformation section (103) measured at the first and last two test points of the barrier; wherein, The top burial depth of the first deformation resistance section (101) at the test point h 1T =0, bottom burial depth h 1B = h 2T ; The top burial depth of the second deformation resistance section (102) at the test point h 2T =Min( H 1, H 2)- h 0- h A , bottom burial depth h 2B =Max( H 1, H 2)+ h 0+ h A ;if h 2T <0, then let h 2T =0; if h 2B > h max , then let h 2B = h max ; The top burial depth of the free deformation section (103) at the test point h 3T = h 2B , bottom burial depth h 3B = h max ; In the formula, Min( H 1, H 2) Indicates H 1 and H The minimum value of 2, H 1 indicates the depth of excavation of contaminated soil at the test point; H 2 indicates the excavation depth of the foundation pit at the test point; h 0 represents the tolerance height of the second deformation resistance section (102); h A represents the calibrated height of the second deformation resistance section (102); Max( H 1, H 2) Indicates H 1 and H The maximum value among 2; h max It represents the sum of the top burial depth of the aquiclude in the stratum and the depth of the barrier embedded in the aquiclude.

4. The method for constructing an anti-coupling type barrier for a contaminated site according to claim 3, characterized in that: Said h 0The value range is 1 to 3 meters.

5. The method for constructing an anti-coupling type barrier for a contaminated site according to claim 3, characterized in that: The correction height of the second anti-deformation section (102) is calculated according to formula (1): Formula (1) In the formula, a represents the coefficient related to the width of the barrier, dimensionless; w Indicates the width of the barrier, in meters; b It is the coefficient related to the permeability coefficient of the barrier and the permeability coefficient of the in-situ soil layer, in m; k c It represents the permeability coefficient of the barrier in cm / s; k s It represents the permeability coefficient of the in-situ soil layer, in cm / s.

6. The method for constructing an anti-coupling type barrier for a contaminated site according to claim 5, characterized in that: Said a The value range is 0.3~0.8, w The value range is 0.6~1.2m, b The value range is 0.5~1.5m. k c For 10 -6 cm / s or 10 -7 cm / s; if the in-situ soil layer spans multiple soil layers, then k s The value is the permeability coefficient corresponding to the soil layer with the largest permeability coefficient.

7. The method for constructing an anti-coupling type barrier for a contaminated site according to claim 1, characterized in that: The compression modulus of the first deformation-resistant section (101) is 2 to 4 times the average compression modulus of the in-situ soil layer within the depth range of the soil layer into which it is buried; The compression modulus of the second deformation-resistant section (102) is 5 to 10 times the average compression modulus of the in-situ soil layer within the depth range in which the second deformation-resistant section (102) is buried.

8. The method for constructing an anti-coupling type barrier for a contaminated site according to claim 7, characterized in that: The compression modulus of the free deformation section (103) is 90-110% of the average compression modulus of the in-situ soil layer within the depth range of the soil layer into which it is buried.

9. The method for constructing a contaminated site anti-coupling barrier according to claim 1, characterized in that: The step 60 specifically includes: constructing the barrier by sections, and the construction process of each barrier is as follows: Step 601, filling a barrier filler into the formation according to the height and compression modulus of the free deformation section (103) to form the free deformation section (103); Step 602, according to the height and compression modulus of the second deformation resistance section (102), a barrier filler is filled above the free deformation section (103) of the formation to form the second deformation resistance section (102); Step 603, according to the height and compression modulus of the first deformation resistance section (101), a barrier filler is filled above the second deformation resistance section (102) of the formation to form the first deformation resistance section (101), thereby building a barrier.

10. The method for constructing an anti-coupling type barrier for a contaminated site according to claim 1, characterized in that: In step 60, after one barrier is constructed, the next adjacent barrier is constructed along the proposed construction direction of the barrier.

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