A pollution-resistant, anti-coupling structure for contaminated sites

Abstract

The present invention belongs to the field of structures in contaminated sites, and discloses a coupling-type pollution-resistant bearing structure for contaminated sites, which can enhance the dual functions of blocking pollutants and maintaining the stability of foundation pits, and minimize the influence of the structure on the stress state of deep soil in contaminated sites. The structure is built in sections, and a transition zone is provided between two adjacent sections; each section includes a first resistance deformation section, a second resistance deformation section and a free deformation section, and the first resistance deformation section, the second resistance deformation section and the free deformation section are connected in sequence from top to bottom; the compression modulus of the second resistance deformation section is greater than the compression modulus of the first resistance deformation section, and the compression modulus of the first resistance deformation section is greater than the compression modulus of the free deformation section.

Description

Technical Field

[0001] The invention belongs to the field of structures in polluted sites, and in particular, relates to an anti-coupling type pollution-proof bearing structure used in polluted sites. Background Art

[0002] In the contaminated site remediation project, a structure that can block the migration of pollutants and remove the soil pressure on the side wall of the foundation pit is usually built to ensure the construction safety of the contaminated site and the surrounding plots during the contaminated site remediation process. This structure can be called a pollution-blocking bearing structure. For contaminated sites where pollutants have spread to deep confined water aquifers, the pollution-blocking bearing structure is generally embedded in the impermeable layer below the confined water aquifer. Therefore, the design depth of the pollution-blocking bearing structure is relatively large. In order to facilitate construction and tend to be conservative in design ideas, the pollution-blocking bearing structure is usually designed as a homogeneous wall structure, that is, the parameters such as anti-seepage and pollution interception, mechanical properties, etc. of the pollution-blocking bearing structure along the depth or direction remain unchanged. Although such a design can ensure the stability of the mechanical properties of the shallow pollution-blocking bearing structure, for the deep pollution-blocking bearing structure, the structure with greater rigidity cannot produce coordinated deformation with the surrounding soil, which has a greater impact on the mechanical properties of the in-situ soil layer and produces greater uncertainty in the design of buildings during site development. In addition, high-rigidity pollution-resistant load-bearing structures often have greater strength, which often produces a greater negative impact on foundation pit excavation and underground structure construction during site development.

[0003] Therefore, for contaminated sites where pollutants spread to deep confined water aquifers, the contaminated soil needs to be excavated during the site remediation process, and when the site development after remediation requires foundation pit excavation, how to optimize the design of temporary pollution-blocking and load-bearing structures and minimize the impact of the pollution-blocking and load-bearing structures on the stress state of the deep soil of the site is a technical challenge faced by technical personnel in this field. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide an anti-coupling type pollution-proof bearing structure for a contaminated site, which can enhance the dual functions of isolating pollutants and maintaining the stability of the foundation pit, and minimize the impact of the structure on the stress state of the deep soil in the contaminated site.

[0005] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0006] A coupling-type pollution-resistant bearing structure for use in a polluted site, wherein the structure is constructed in sections, and a transition zone is provided between two adjacent sections; each section of the structure comprises a first resistance deformation section, a second resistance deformation section and a free deformation section, and the first resistance deformation section, the second resistance deformation section and the free deformation section are sequentially connected from top to bottom; the compression modulus of the second resistance deformation section is greater than that of the first resistance deformation section, and the compression modulus of the first resistance deformation section is greater than that of the free deformation section.

[0007] 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 its burial 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 its burial soil layer; and 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 its burial soil layer.

[0008] As a preferred example, the height of the first deformation resistance section in each structure is the arithmetic mean of the heights of the first deformation resistance section measured at the first and last test points of the structure; the height of the second deformation resistance section of each structure is the arithmetic mean of the heights of the second deformation resistance section measured at the first and last test points of the structure; the height of the free deformation section of each structure is the arithmetic mean of the heights of the free deformation section measured at the first and last test points of the structure; wherein the top buried depth of the first deformation resistance 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, 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 = hmax ; The top burial depth of the free deformation section 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 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 buried depth of the aquiclude in the stratum and the depth of the structure embedded in the aquiclude.

[0009] As a preferred example, the value range of h0 is 1 to 3 m.

[0010] As a preferred example, the correction height of the second deformation resistance section is calculated according to formula (1):

[0011] Formula (1)

[0012] In the formula, a It represents the coefficient related to the width of the structure, dimensionless; w Indicates the width of the structure, in meters; b It indicates the coefficient related to the permeability coefficient of the structure and the permeability coefficient of the in-situ soil layer, and the unit is m; k s It represents the permeability coefficient of the in-situ soil layer in cm / s; k c It represents the permeability coefficient of the structure, in cm / s.

[0013] 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.

[0014] As a preferred example, the transition zone includes a first transition resistance deformation section, a second transition resistance deformation section and a transition free deformation section, and the first transition resistance deformation section, the second transition resistance deformation section and the transition free deformation section are connected in sequence from top to bottom.

[0015] As a preferred example, the compression modulus of the first transition resistance to deformation section is the larger value of the compression modulus of the first resistance to deformation sections in the adjacent two side structures; the compression modulus of the second transition resistance to deformation section is the larger value of the compression modulus of the second resistance to deformation sections in the adjacent two side structures; the compression modulus of the transition free deformation section is the larger value of the compression modulus of the free deformation sections in the adjacent two side structures.

[0016] As a preferred example, the height of the first transition resistance deformation section is the arithmetic mean of the heights of the first resistance deformation sections in the adjacent two side structures; the height of the second transition resistance deformation section is the arithmetic mean of the heights of the second resistance deformation sections in the adjacent two side structures; the height of the transition free deformation section is the arithmetic mean of the heights of the free deformation sections in the adjacent two side structures.

[0017] As a preferred example, the length of the transition zone is 5 to 10 m; the length of each structure is 40 to 80 m.

[0018] Compared with the prior art, the anti-coupling pollution-proof bearing structure for contaminated sites of the present invention can enhance the dual functions of blocking pollutants and maintaining the stability of foundation pits, and minimize the influence of the structure on the stress state of the deep soil of the contaminated site. A transition zone is provided between two adjacent structures; each structure includes a first resistance deformation section, a second resistance deformation section and a free deformation section connected in sequence from top to bottom; the compression modulus of the second resistance deformation section is greater than the compression modulus of the first resistance deformation section, and the compression modulus of the first resistance deformation section is greater than the compression modulus of the free deformation section. In the process of excavating the contaminated soil for the restoration of the contaminated site and excavating the foundation pit for the safe development and utilization of the site after restoration, the first resistance deformation section and the second resistance deformation section of the structure can effectively resist the deformation of the structure caused by external disturbances and maintain the stability of the structure; and the free deformation section produces cooperative deformation with the in-situ soil and maintains the anti-seepage and pollution interception performance of the structure. In addition, the structural structure can effectively reduce the use of soil modification materials, reduce construction costs, and increase the environmental friendliness of the structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is a cross-sectional view of an embodiment of the present invention in a contaminated site;

[0020] Figure 2 is a top view of an embodiment of the present invention in a contaminated site;

[0021] Figure 3 It is a schematic diagram of the locations of the depth of the structure, the depth of the contaminated soil excavation and the depth of the foundation pit excavation according to an embodiment of the present invention;

[0022] Figure 4 It is a stratum distribution map of the contaminated site applied in the embodiment of the present invention.

[0023] In the figure: structure 1, first resistance to deformation section 101, second resistance to deformation section 102, free deformation section 103, transition zone 2, first transition resistance to deformation section 201, second transition resistance to deformation section 202, transition free deformation section 203, fill layer 301, silty silty clay layer 302, silty sand and silty clay layer 303, silty clay and silty soil layer 304, first structure 501, second structure 502, contaminated soil 6, contaminated land boundary 7, excavation pit first partition 801, excavation pit second partition 802. DETAILED DESCRIPTION

[0024] 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.

[0025] 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 structures in different depth ranges are not exactly the same. Therefore, the present invention proposes a coupling-resistant structure in combination with the different roles of structures at different depths in blocking pollutants and supporting foundation pits. Specifically, the coupling-resistant structure of the present invention sets different stiffnesses for structures in different depth ranges according to the functional requirements for structures during site remediation and development and utilization. The structure located above the groundwater level is the first deformation resistance section 101. The first deformation resistance section 101 is used to resist the deformation of the structure caused by stratum deformation during excavation and maintain structural stability. 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 its buried soil layer. The structure located below the groundwater level and above the foundation pit excavation depth is the second deformation resistance section 102. The second deformation resistance section is used to resist the deterioration of the stiffness of the structure under the action of the dry-wet cycle caused by the rise and fall of groundwater. The compression modulus of the second deformation resistance 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 structure below the excavation depth of the foundation pit is the free deformation section 103. The free deformation section 103 ensures that the stress-strain state of the deep soil is not significantly affected after the construction of the structure, and produces coordinated deformation with the in-situ soil layer, which can minimize the disturbance of the formation during the construction process. 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 its buried soil layer. The structure that meets the above characteristics is called an anti-coupling structure.

[0026] like Figure 1 As shown, an anti-coupling type pollution-proof bearing structure for a polluted site according to an embodiment of the present invention, the structure 1 is built in sections, and a transition zone 2 is provided between two adjacent structures 1; each structure 1 comprises a first resistance deformation section 101, a second resistance deformation section 102 and a free deformation section 103, and the first resistance deformation section 101, the second resistance deformation section 102 and the free deformation section 103 are sequentially connected from top to bottom; the compression modulus of the second resistance deformation section 102 is greater than the compression modulus of the first resistance deformation section 101, and the compression modulus of the first resistance deformation section 101 is greater than the compression modulus of the free deformation section 103.

[0027] The structure of the above embodiment includes a first deformation resistance section 101, a second deformation resistance section 102 and a free deformation section 103 arranged in sequence from top to bottom, and 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. The compression modulus of the same structure 1 is different, the compression modulus of the second deformation resistance section 102 located in the middle is the largest, the compression modulus of the first deformation resistance section 101 located in the upper part is the second, and the compression modulus of the free deformation section 103 located in the lower part is the smallest. For sites where contaminated soil needs to be excavated during the repair process and where foundation pits need to be excavated for site development and utilization after repair, the roles played by structures in different depth ranges are not exactly the same. The rigidity of the structure 1 is designed in sections according to its burial depth, which can give full play to the supporting role of the structure 1 on the excavated foundation pit and keep the foundation pit stable. By optimizing the rigidity of the structure 1, the amount of material used in the structure can be effectively reduced. At the same time, the selection of deep structures can produce retreating deformation with the original stratum deformation, effectively reducing the impact of the structures on the stratum stress environment and making construction activities more adapted to the natural environment.

[0028] In addition, the structure 1 is constructed in sections, and a transition zone 2 is provided between two adjacent structures 1. When the structure 1 is constructed in sections, the contact position between the two adjacent structures 1 is the weak point of the structure because the construction machinery needs to be transferred or terminally constructed. In addition, in two adjacent structures 1, the heights of the corresponding two first resistance deformation sections 101, the heights of the corresponding two second resistance deformation sections 102, and the heights of the corresponding two free deformation sections 103 are often different. If the height of the junction of the two structures 1 changes suddenly, it will cause a change in the service performance parameters of the structure 1, and the long-term service of the structure 1 will not be utilized. Therefore, a transition zone 2 is provided at the junction of the two structures 1 to achieve the height transition of the first resistance deformation section 101, the second resistance deformation section 102 and the free deformation section 103 between the two adjacent structures 1, thereby enhancing the stability of the structure.

[0029] The structures in the above-mentioned embodiments are designed with compression modulus according to the stiffness of the in-situ soil layer. Through the change of compression modulus at different depths, the shallow structures can effectively resist the deformation of the shallow in-situ soil layer and achieve structural stability of the excavated foundation pit; while the deep structures can deform in coordination with the in-situ soil layer and maintain the stress state of the in-situ soil layer.

[0030] Preferably, 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 buried soil layer. The stiffness of the first deformation-resistant section 101 is within this range, which can resist the deformation of the structure 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-resistant 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. The stiffness of the second deformation-resistant section 102 is within this range, which can resist the deterioration of the stiffness of the structure under the action of 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 the free deformation section 103 is within this range, which can ensure that the stress-strain state of the deep soil is not significantly affected after the construction of the structure, and the in-situ soil layer produces cooperative deformation, which can minimize the disturbance of the stratum during the construction process. The stiffness of each section of the structure is characterized by the compression modulus.

[0031] Preferably, the height of the first deformation resistance section 101 in each structure is the arithmetic mean of the heights of the first deformation resistance section 101 measured at the first and last test points of the structure; the height of the second deformation resistance section 102 in each structure is the arithmetic mean of the heights of the second deformation resistance section 102 measured at the first and last test points of the structure; the height of the free deformation section 103 in each structure is the arithmetic mean of the heights of the free deformation section 103 measured at the first and last test points of the structure. 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 2. Figure 3 As shown, 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. Preferably, h 0 value range is 1~3m; 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 structure embedded in the aquiclude.

[0032] Preferably, the correction height of the second anti-deformation section 102 is calculated according to formula (1):

[0033] Formula (1)

[0034] In the formula, a It represents the coefficient related to the width of the structure, dimensionless; w Indicates the width of the structure, in meters; b It indicates the coefficient related to the permeability coefficient of the structure and the permeability coefficient of the in-situ soil layer, and the unit is m; k s It represents the permeability coefficient of the in-situ soil layer in cm / s; k c represents the permeability coefficient of the structure, in cm / s. 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.

[0035] The height correction of the second deformation resistance section 102 is determined by the width of the structure and the ratio of the in-situ soil permeability coefficient to the structure permeability coefficient. h A Refined calculations can effectively consider the impact of changes in the foundation pit dewatering curve on changes in the moisture content of the structure, thereby incorporating the degradation process of the structure's service performance under the action of dry-wet cycles into the design of the structure's height.

[0036] Preferably, the transition zone 2 includes a first transition resistance deformation section 201, a second transition resistance deformation section 202 and a transition free deformation section 203, which are connected in sequence from top to bottom. Consistent with the layered structure of the first resistance deformation section 101, the second resistance deformation section 102 and the free deformation section 103 of the two adjacent structures 1, the structure of the transition zone 2 is also divided into three sections, namely the first transition resistance deformation section 201, the second transition resistance deformation section 202 and the transition free deformation section 203. Dividing the transition zone 2 into three sections along the depth direction can simultaneously achieve the yielding coupling effect between the transition zone 2 and the surrounding in-situ soil layer.

[0037] Preferably, the compression modulus of the first transition resistance deformation section 201 is the larger value of the compression modulus of the first resistance deformation section 101 in the adjacent two-side structures. The compression modulus of the second transition resistance deformation section 202 is the larger value of the compression modulus of the second resistance deformation section 102 in the adjacent two-side structures. The compression modulus of the transition free deformation section 203 is the larger value of the compression modulus of the free deformation section 103 in the adjacent two-side structures. The contact position between the two adjacent structures 1 caused by the construction of the structure 1 in sections is the weak point of the structure. Therefore, the conservative design idea is to design the compression modulus of the first transition resistance deformation section 201, the second transition resistance deformation section 202 and the transition free deformation section 203 of the transition zone 2 to be the larger value of the compression modulus of the corresponding sections of the structures in the adjacent two-side structures.

[0038] Preferably, the height of the first transition resistance deformation section 201 is the arithmetic mean of the heights of the first resistance deformation section 101 in the adjacent two-side structures; the height of the second transition resistance deformation section 202 is the arithmetic mean of the heights of the second resistance deformation section 102 in the adjacent two-side structures; the height of the transition free deformation section 203 is the arithmetic mean of the heights of the free deformation section 103 in the adjacent two-side structures. Setting the height of each sub-segment of the transition zone 2 to the arithmetic mean of the height of the corresponding sub-segment in the adjacent two-side structures 1 can effectively reduce the height mutation of each sub-segment contact position at the junction of the adjacent two-side structures and improve the overall homogeneity of the structure. In addition, the structure can increase construction efficiency while ensuring that the structure has a certain degree of homogeneity.

[0039] Preferably, the length of the transition zone is 5 to 10 m; the length of each structure is 40 to 80 m. The length of the transition zone is mainly determined based on the current construction equipment and construction technology, and this range can ensure the construction quality and efficiency of the transition section structure. If the length of the transition zone is too long, the construction period of the transition zone structure will be too long, while if the length of the transition zone is too short, the service parameters (permeability coefficient, compression modulus, etc.) of the transition zone structure along the direction of the structure will change greatly, resulting in more weak points.

[0040] During the remediation of contaminated sites, the structures have the functions of blocking pollutants and supporting foundation pits. The structures have a certain degree of rigidity. During the excavation of contaminated soil, the structures are maintained from significant deformation and the foundation pit structure is maintained stable. Similarly, the structures can maintain the stability of the foundation pit structure during site development. Usually, the excavation depth of contaminated site soil and the excavation depth of the foundation pit for site development are not the same, and the depths of the two directly determine the rigidity design requirements of the structures. The greater the rigidity of the structure, the greater the amount of structural material that needs to be added, thereby increasing the construction cost. The present invention can effectively reduce the amount of structural material used by optimizing the design of the structural rigidity; at the same time, the deep structure can produce a concession deformation with the original stratum deformation, effectively reducing the impact of the structure on the stratum stress environment, making the construction activities more adaptable to the natural environment.

[0041] The following provides examples and comparative examples to verify that the structure of the present invention can effectively reduce the amount of structure material used.

[0042] Example

[0043] like Figure 2 As shown in the figure, referring to the previous investigation data of the contaminated site and the risk control plan of the contaminated site, it is necessary to build a structure at the boundary 7 of the contaminated land to separate the contaminated soil 6 from the surrounding clean soil. The length of the structure is 120m. Carry out geotechnical engineering survey of the contaminated site to determine the stratum distribution of the proposed construction direction of the structure. After the survey, if Figure 4As shown, the strata in the proposed construction direction of the structure are, from top to bottom, fill layer 301, silty silty clay layer 302, silty sand and silty clay layer 303, and silty clay and silty soil layer 304. Among them, silty clay and silty soil layer 304 is equivalent to an impermeable layer, and silty silty clay layer 302 and silty sand and silty clay layer 303 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 303 was already polluted. The contaminated soil was excavated out of the site, so the excavation depth H1 was 7.5m. Considering that the remediation process may cause pollution to the groundwater in the silt sand and silty clay layer 303, the structure was embedded in the silty clay and silty soil layer 304 (aquiclude).

[0045] According to the safe reuse plan for the remediation of contaminated sites, the construction pit is excavated in two areas during the site redevelopment process. The excavation depth of the first excavation pit 801 is 9.0m, and the excavation depth of the second excavation pit 802 is 4.5m. The length of the two partitions along the direction of the structure is 60m, and the width perpendicular to the direction of the structure is 120m, so the structure is divided into two sections for design and construction. The length of the contaminated soil excavation partition during the contaminated site remediation process is equal to the length of the construction pit excavation partition, and the width of the contaminated soil excavation partition is equal to the width of the construction pit excavation partition.

[0046] Each structure is located in a partition of the excavated foundation pit. The length of the first structure 501 is 55 m and the width is 0.6 m; the length of the transition zone 2 is 10 m and the width is 0.6 m; the length of the second structure 502 is 55 m and the width is 0.6 m. The parameters of the structures are shown in Table 1.

[0047] Table 1 Structure parameters

[0048]

[0049] In-situ soil is collected to conduct a test on the dosage optimization of the building material. In this embodiment, the compression modulus requirement of the free deformation section 103 is relatively low, and bentonite is used to modify the in-situ soil. According to experience, the dosage is 6% of the dry weight of the in-situ soil.

[0050] The first deformation resistance section 101 and the second deformation resistance section 102 require that the construction material of the structure has a large compression modulus. In this embodiment, cement activated bentonite is used to modify the in-situ soil. D (Unit: %) Based on the compression modulus of the structure 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, with a value of 0.2 and a unit of MPa. -1 In order to facilitate construction, the dosage D Take it as an integer and round it up. For example, the compression modulus of the first deformation resistance section in the first structure is 23.25MPa, and the dosage D 2+0.2×23.25=6.65%, rounded up to 7%. For another example, the compression modulus of the second deformation resistance section in the second structure is 133.27MPa, and the dosage is D 2+0.2×133.27=28.65%, rounded up to 29%. According to the data in Table 1 and the above formula, the dosage of each section of each structure is calculated, and the results are shown in Table 2.

[0051] Table 2 Dosage of in-situ soil modification materials

[0052]

[0053] According to the dosage of the in-situ soil modification material in Table 2, the double-axis mixing method is used to construct the structure. The soil modification material is added in corresponding mass proportions in different sections of each structure, and the construction of the first structure 501 and the second structure 502 is completed in turn.

[0054] Calculate the in-situ soil modification materials required to build the 120m structure of this embodiment. The calculation process is shown in Table 3. 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 the modified material of each section of each structure 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 (or bentonite). In this embodiment, the length of each section of the first structure 501 and the second structure 502 is 55m, and the width is 0.6m; the length of each section of the transition zone 2 is 10m, and the width is 0.6m. For example, the mass of the cement-activated bentonite in the first deformation-resistant section 101 of the first structure 501 is 55×0.6×3.55×1.6×7%=13.12t. For another example, the mass of the bentonite in the free deformation section of the first structure 501 is 55×0.6×9.85×1.6×6%=31.20t. According to Table 3, the amount of cement-activated bentonite is calculated to be 13.12+132.73+2.30+31.15+6.60+194.41=380.31t, and the amount of bentonite is 31.20+5.66+31.05=67.91t.

[0055] Table 3 Modified material dosage

[0056]

[0057] Comparative Example

[0058] The traditional structure design method is adopted, the stiffness of the structure is taken into consideration, and the stiffness of the structure within all depth ranges is the same. For the convenience of comparison, the compression modulus of the structure in this comparative example is set to be the same as the second deformation resistance section of the second structure in the embodiment, that is, 133.27MPa; cement-activated bentonite is selected as the modified material for the in-situ soil, and the corresponding cement-activated bentonite dosage is 29%. The structure is not constructed in sections. The parameters of the entire structure are the same. The length of the entire structure is 120m and the width is 0.6m. The depth of the structure is 23.00m (the same as the maximum depth value of the structure in the embodiment). Let the dry density of the soil layer be 1.6g / cm 3 The calculated amount of cement-activated bentonite is 120×0.6×23.00×1.6×29%=768.38 t.

[0059] By comparison, it can be seen that the amount of modified material used in the embodiment of the present invention can be saved by about 1-(380.31+67.91) / 768.38×100%=41.67%.

[0060] 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 coupling-resistant pollution-blocking bearing structure for use in polluted sites, characterized in that: The structure (1) is constructed in sections, and a transition zone (2) is provided between two adjacent sections of the structure (1); each section of the structure (1) comprises a first deformation resistance section (101), a second deformation resistance section (102) and a free deformation section (103), and the first deformation resistance section (101), the second deformation resistance section (102) and the free deformation section (103) are sequentially connected from top to bottom; the compression modulus of the second deformation resistance section (102) is greater than the compression modulus of the first deformation resistance section (101), and the compression modulus of the first deformation resistance section (101) is greater than the compression modulus of the free deformation section (103); The height of the first deformation resistance section (101) in each structure (1) is the arithmetic average of the heights of the first deformation resistance section (101) measured at the first and last test points of the structure; The height of the second deformation resistance section (102) of each structure (1) is the arithmetic average of the heights of the second deformation resistance section (102) measured at the first and last test points of the structure; The height of the free deformation section (103) of each structure (1) is the arithmetic average of the heights of the free deformation section (103) measured at the first and last test points of the structure; 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 ; 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 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 buried depth of the aquiclude in the stratum and the depth of the structure embedded in the aquiclude; The correction height of the second anti-deformation section (102) is calculated according to formula (1): Formula (1) In the formula, a It represents the coefficient related to the width of the structure, dimensionless; w Indicates the width of the structure, in meters; b It indicates the coefficient related to the permeability coefficient of the structure and the permeability coefficient of the in-situ soil layer, and the unit is m; k s It represents the permeability coefficient of the in-situ soil layer in cm / s; k c It represents the permeability coefficient of the structure, in cm / s.

2. The anti-coupling pollution-proof bearing structure for use in polluted sites according to claim 1 is 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 of the soil layer into which it is buried; 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.

3. The anti-coupling pollution-proof bearing structure for a polluted site according to claim 1 is characterized in that: Said h 0The value range is 1 to 3 meters.

4. The anti-coupling pollution-proof bearing structure for polluted sites according to claim 1 is 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.

5. The anti-coupling pollution-proof bearing structure for a polluted site according to claim 1 is characterized in that: The transition zone (2) comprises a first transition resistance deformation section (201), a second transition resistance deformation section (202) and a transition free deformation section (203), wherein the first transition resistance deformation section (201), the second transition resistance deformation section (202) and the transition free deformation section (203) are connected in sequence from top to bottom.

6. The anti-coupling pollution-proof bearing structure for use in polluted sites according to claim 5 is characterized in that: The compression modulus of the first transition deformation resistance section (201) is the larger value of the compression moduli of the first deformation resistance sections (101) in the adjacent two side structures; The compression modulus of the second transition deformation resistance section (202) is the larger value of the compression modulus of the second deformation resistance sections (102) in the adjacent two side structures; The compression modulus of the transitional free deformation section (203) is the larger value of the compression moduli of the free deformation sections (103) in the adjacent two side structures.

7. The anti-coupling pollution-proof bearing structure for use in polluted sites according to claim 5 is characterized in that: The height of the first transition deformation resistance section (201) is the arithmetic average of the heights of the first deformation resistance sections (101) in the adjacent structures on both sides; The height of the second transition deformation resistance section (202) is the arithmetic average of the heights of the second deformation resistance sections (102) in the adjacent structures on both sides; The height of the transitional free deformation section (203) is the arithmetic average of the heights of the free deformation sections (103) in the adjacent two side structures.

8. The anti-coupling pollution-proof bearing structure for use in polluted sites according to claim 1 is characterized in that: The length of the transition zone is 5 to 10 m; the length of each structure (1) is 40 to 80 m.

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