Construction method for offshore large-deformation ultra-soft soil foundation fly ash landfill reservoir area

Abstract

The invention belongs to the technical field of fly ash landfill, and particularly relates to an offshore large-deformation ultra-soft soil foundation fly ash landfill reservoir area construction method. And then first-time reservoir area implementation, landfill of the reservoir area to the first-time landfill height, second-time reservoir area implementation and landfill of the reservoir area to the second-time landfill height are sequentially carried out, and the steps of second-time reservoir area implementation and landfill are repeatedly carried out until the ground height and the landfill height are designed, and then reservoir area construction is completed. According to the construction method, construction of the offshore fly ash landfill reservoir area is proposed for the first time, spoil is used as a reclamation material, solidified sea mud is used as an impermeable layer, a reservoir area foundation is subjected to composite foundation treatment, and vertical sea mud solidified walls are arranged on the periphery of the reservoir area, so that synchronous implementation of reservoir area construction and landfill is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of fly ash landfill, and in particular to a method for constructing a fly ash landfill storage area on an offshore large-deformation ultra-soft soil foundation. Background Art

[0002] With the development of urban construction and economy, the disposal of large amounts of domestic and construction waste faces a huge challenge. Landfill is the most common method of solid waste disposal at home and abroad, but the continuous acceptance and disposal of solid waste landfills has made the storage capacity of more and more landfills close to saturation. New landfills have a particularly large demand for land, and land around cities is in short supply. Therefore, the demand for the construction of offshore landfills continues to rise.

[0003] Compared with landfill projects, offshore solid waste landfills face the influence of complex hydrodynamic environment, changeable marine climate, deep marine sedimentary strata and other factors. Leakage of solid waste or generated leachate will directly pollute the marine environment. Therefore, it is more critical to prevent the spread of pollutants in offshore landfills. The foundation of offshore solid waste landfills is often a deep marine sedimentary silt layer with large foundation deformation. The traditional reservoir structure base and slope have serious uneven settlement phenomena, facing the problem of high difficulty in foundation treatment. In addition, the construction of the reservoir area requires a large amount of reclamation materials, and traditional sand and gravel are in short supply. Not only does it face the problems of high cost and serious environmental damage, but the construction period of the reservoir area is long and the investment is large.

[0004] Wu Dongqing et al. (Research progress on the recycling of solid waste for land reclamation in Singapore [J]. Environmental Science Research, 2018, 31(07): 1174-1181) studied the "new soil" technology of converting Singapore's sludge and waste incineration ash into "sludge-ash waste material matrix (MC-IBA Matrix)" for land reclamation using the chemical-physical composite method (CPCM). They found that "new soil" is feasible and superior as a reclamation material from both an environmental and engineering perspective. This green technology can solve the dual problems of lack of landfill land and reclamation materials, but it did not propose a specific, safe and reliable method for constructing an offshore landfill area.

[0005] Based on the above problems, technical personnel in this field urgently need to provide an environmentally friendly, economical, safe and reliable offshore landfill construction method to solve the problems faced in the construction of existing offshore landfill areas, such as high difficulty in foundation treatment, shortage and high cost of reclamation materials, serious environmental damage and long reservoir construction period. Summary of the invention

[0006] This application innovatively proposes the construction of an offshore fly ash landfill area, and provides a method for constructing an offshore fly ash landfill area with large deformation and ultra-soft soil foundation, which has the advantages of high efficiency, environmental protection, economy, safety and reliability. The specific technical solution is described as follows.

[0007] A method for constructing a fly ash landfill area on an offshore large deformation ultra-soft soil foundation comprises the following steps: Step S1: Determine the landfill height and storage capacity of the storage area; Step S2: first reservoir area implementation; Step S3: landfilling the storage area to the first landfill height; Step S4: Second reservoir area implementation; Step S5: landfilling the storage area to the second landfill height; Step S6: Repeat steps S4 and S5 until the designed ground height and the designed landfill height are reached.

[0008] Furthermore, the step S1 is specifically as follows: according to the landfill standard of the fly ash landfill area, a composite foundation treatment method is selected, the composite foundation settlement is calculated, and the landfill height and storage capacity of the storage area are determined.

[0009] Furthermore, the step S2 includes: Step S21: After the soil is backfilled on the water for the first time and a dam is formed around the reservoir area, a vertical anti-seepage wall is constructed; Step S22: laying geonet mats and drainage pads, burying groundwater pumping and drainage facilities, and then constructing composite foundation piles; Step S23: laying geotextiles, then constructing an anti-seepage layer on top of the geotextiles, and at the same time constructing the first height section of the sea mud solidification wall around the reservoir area; Step S24: laying geomembranes and geotextiles in the reservoir area, and constructing leachate diversion layers and leachate drainage facilities.

[0010] Furthermore, the step S4 specifically includes: backfilling soil around the reservoir area, and constructing the second height section of the sea mud solidification wall and the wall geomembrane around the reservoir area.

[0011] Furthermore, the anti-seepage layer in step S23 is composed of solidified sea mud, which can achieve rapid construction.

[0012] Furthermore, the leachate drainage facility in step S24 includes a leachate drainage pipe.

[0013] Furthermore, the geotextile in step S23 is laid on top of the drainage cushion layer.

[0014] Furthermore, the geomembrane in the reservoir area in step S24 is laid above the anti-seepage layer.

[0015] Furthermore, the drainage cushion layer in step S22 also serves as a groundwater drainage layer, and the liquid level meter automatically starts and stops the drainage pump to control the groundwater level.

[0016] Furthermore, the materials used for the backfill construction in step S21 and step S4 are all abandoned soil, and a fill layer is finally formed after the backfill construction.

[0017] Furthermore, the landfill materials in step S3 and step S5 are both solidified fly ash bags.

[0018] Compared with the prior art, the advantages and effects of this application are as follows: 1. The present invention utilizes abandoned soil as land reclamation material and solidified sea mud as an anti-seepage layer. The reservoir foundation adopts composite foundation treatment, and vertical sea mud solidification walls are set around the reservoir area, thereby realizing the simultaneous implementation of reservoir construction and landfill. The present application innovatively proposes a green backfilling treatment technology using abandoned soil and solidified sea mud as reservoir construction materials, thereby realizing resource utilization, using local materials, and being low-carbon and environmentally friendly; and breaking through the disadvantages of uneven settlement of slope boundaries in traditional reservoir areas.

[0019] 2. The present invention innovatively proposes a treatment technology for the vertical boundary of the reservoir area, using a variable-section sea mud solidification wall as a retaining structure to achieve the goal of rapid landfill in stages.

[0020] 3. The present invention innovatively proposes a composite foundation treatment method, which does not require prior foundation treatment. The drainage cushion layer also serves as a groundwater drainage layer. The liquid level meter automatically starts and stops the drainage pump to control the groundwater level.

[0021] 4. The present invention innovatively proposes a treatment technology for solidified sea mud as the anti-seepage layer of the reservoir area, replacing clay and achieving the goal of rapid construction.

[0022] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application so that it can be implemented in accordance with the contents of the specification, and to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the following is a detailed description of the preferred embodiments of the present application in conjunction with the accompanying drawings as follows.

[0023] Based on the detailed description of the specific embodiments of the present application in combination with the accompanying drawings below, those skilled in the art will become more aware of the above and other objects, advantages and features of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings required for use in the embodiments or the prior art descriptions are briefly introduced below. Obviously, the drawings described below are some embodiments of the present application. For those skilled in the art, other drawings can also be obtained based on these drawings without creative work. In all drawings, similar elements or parts are generally identified by similar reference numerals. In the drawings, each element or part is not necessarily drawn according to the actual scale.

[0025] in: Figure 1 This is a flow chart of a method for constructing a fly ash landfill area on an offshore large deformation ultra-soft soil foundation provided by the present application; Figure 2 It is a plan view of a fly ash landfill area on an offshore large deformation ultra-soft soil foundation provided by the applicant; Figure 3 This is a cross-sectional view of a fly ash landfill area on an offshore large deformation ultra-soft soil foundation provided by the applicant. Among them: 1-composite foundation pile foundation; 2-sea mud solidification wall; 3-groundwater pumping and drainage facilities; 4-drainage cushion layer; 5-anti-seepage layer; 6-geomembrane in the reservoir area; 7-fill layer; 8-leachate diversion layer; 9-leachate drainage pipe; 10-vertical anti-seepage wall. DETAILED DESCRIPTION

[0026] To make the purpose, technical scheme and advantages of the embodiment of the present application clearer, the technical scheme in the embodiment of the present application will be clearly and completely described below in conjunction with the accompanying drawings in the embodiment of the present application. Obviously, the described embodiment is a part of the embodiment of the present application, rather than all of the embodiments. In the following description, specific details such as specific configuration and components are provided only to help fully understand the embodiments of the present application. Therefore, it should be clear to those skilled in the art that various changes and modifications can be made to the embodiments described herein without departing from the scope and spirit of the present application. In addition, for clarity and brevity, the description of known functions and structures is omitted in the embodiment.

[0027] It should be understood that the references to "one embodiment" or "this embodiment" throughout the specification mean that the specific features, structures, or characteristics associated with the embodiment are included in at least one embodiment of the present application. Therefore, the references to "one embodiment" or "this embodiment" appearing throughout the specification do not necessarily refer to the same embodiment. In addition, these specific features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

[0028] In addition, the present application may repeat reference numerals and / or letters in different examples. This repetition is for the purpose of simplicity and clarity, and does not in itself indicate the relationship between the various embodiments and / or settings discussed.

[0029] The term "and / or" in this article is only a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can mean: A exists alone, B exists alone, and A and B exist at the same time. The term " / and" in this article describes another type of association object relationship, indicating that there can be two relationships. For example, A / and B can mean: A exists alone, and A and B exist alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0030] The term "at least one" in this article is merely a description of the association relationship of associated objects, indicating that there may be three relationships. For example, at least one of A and B can mean: A exists alone, A and B exist at the same time, and B exists alone.

[0031] It should also be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusions.

[0032] Example 1 This embodiment introduces a method for constructing a fly ash landfill reservoir area on an offshore large deformation ultra-soft soil foundation. The reservoir area is built on the upper part of the seabed hard soil layer. The construction method is shown in the attached Figure 1 , including the following steps: Step S1: Determine the landfill height and storage capacity of the storage area; Step S2: first reservoir area implementation; Step S3: landfilling the storage area to the first landfill height; Step S4: Second reservoir area implementation; Step S5: landfilling the storage area to the second landfill height; Step S6: Repeat steps S4 and S5 until the designed ground height and the designed landfill height are reached, thus achieving the goal of rapid landfill construction in stages.

[0033] Preferably, the step S1 specifically comprises: selecting a composite foundation treatment method according to the landfill standard of the fly ash landfill storage area, calculating the composite foundation settlement, and determining the landfill height and storage capacity of the storage area.

[0034] Preferably, the step S4 specifically includes: backfilling soil around the reservoir area, and constructing the second height section of the sea mud solidification wall 2 and the wall geomembrane around the reservoir area.

[0035] Preferably, the material used for the backfill construction in step S4 is abandoned soil, and a backfill layer 7 is finally formed after the backfill construction.

[0036] Preferably, the landfill materials in step S3 and step S5 are both solidified fly ash bags.

[0037] Please refer to the attached drawing for the plan view of the fly ash landfill area on an offshore large deformation ultra-soft soil foundation constructed in this embodiment. Figure 2 , see the attached cross-sectional view Figure 3 .

[0038] The technical effect achieved by this embodiment is: this embodiment innovatively proposes a processing technology for the vertical boundary of the reservoir area, uses a variable-section sea mud solidification wall as a retaining structure, and achieves the goal of rapid landfill in stages.

[0039] Example 2 Based on the above-mentioned embodiment 1, this embodiment introduces a specific method for implementing the first reservoir area in a method for constructing a fly ash landfill reservoir area on an offshore large deformation ultra-soft soil foundation, including the following steps: Step S21: After the soil is backfilled on the water for the first time and a dam is formed around the reservoir area, a vertical anti-seepage wall 10 is constructed; Step S22: laying geonet mats and drainage cushion layers 4, burying groundwater pumping and drainage facilities 3, and then burying composite foundation piles 1; Step S23: laying geotextile, then constructing an anti-seepage layer 5 on the geotextile, and at the same time constructing the first height section of the sea mud solidification wall 2 around the reservoir area; Step S24: laying geomembrane 6 and geotextile in the reservoir area, and constructing leachate diversion layer 8 and leachate drainage facilities.

[0040] Preferably, the anti-seepage layer 5 in step S23 is composed of solidified sea mud, and the material used for backfill construction in step S21 is abandoned soil; through the green backfill treatment technology, the disadvantage of uneven settlement of the slope boundary of the traditional reservoir area is broken through.

[0041] Preferably, the leachate drainage facility in step S24 includes a leachate drainage pipe 9.

[0042] Preferably, in step S22 , the geogrid is laid on top of the vertical anti-seepage wall 10 , the drainage cushion layer 4 is laid above the geogrid, and the composite foundation piles 1 are equidistantly placed between the vertical anti-seepage walls 10 .

[0043] Preferably, the geotextile in step S23 is laid on top of the drainage cushion layer 4.

[0044] Preferably, the geomembrane 6 in the reservoir area in step S24 is laid above the anti-seepage layer 5, a geotextile is laid above the geomembrane 6 in the reservoir area, a leachate diversion layer 8 is constructed above the geotextile, and a layer of geogrid is laid on the top of the leachate diversion layer 8.

[0045] Preferably, the drainage cushion layer 4 also serves as a groundwater drainage layer, and the liquid level meter automatically starts and stops the drainage pump to control the groundwater level.

[0046] The technical effects achieved by this embodiment are as follows: this embodiment uses abandoned soil as land reclamation material, uses solidified sea mud as an impermeable layer, adopts composite foundation treatment for the reservoir foundation, and sets vertical sea mud solidification walls around the reservoir area, thereby realizing the simultaneous implementation of reservoir construction and landfill; innovatively proposes a green backfill treatment technology using abandoned soil and solidified sea mud as reservoir construction materials, thereby realizing resource utilization, using local materials, and being low-carbon and environmentally friendly; breaking through the drawbacks of uneven settlement of slope boundaries in traditional reservoir areas; innovatively proposes a composite foundation treatment method, in which the foundation does not need to be pre-treated, and the drainage cushion layer also serves as a groundwater drainage layer. The liquid level meter automatically starts and stops the pumping pump to control the groundwater level; innovatively proposes a treatment technology for solidified sea mud as an impermeable layer in the reservoir area to replace clay and achieve the goal of rapid construction.

[0047] The above description is only the preferred embodiment of the present invention, which does not limit the protection scope of the present invention. For those skilled in the art, the present invention can be modified and varied in various ways. Within the spirit and principle of the present invention, any change, modification, replacement, integration and parameter change of these embodiments by conventional substitution or capable of achieving the same function without departing from the principle and spirit of the present invention shall fall within the protection scope of the present invention.

Claims

1. A method for constructing a fly ash landfill area on an offshore large deformation ultra-soft soil foundation, characterized in that: The following steps are involved: Step S1: Determine the landfill height and storage capacity of the storage area; Step S2: first reservoir area implementation; Step S3: landfilling to the first landfill height; Step S4: Second reservoir area implementation; Step S5: landfilling to the second landfill height; Step S6: repeating steps S4 and S5 until the designed ground height and the designed landfill height are reached; The step S2 comprises: Step S21: After the soil is backfilled on the water for the first time and a dam is formed around the reservoir area, a vertical anti-seepage wall (10) is constructed; Step S22: laying a geonet mat and a drainage cushion layer (4), burying groundwater pumping and drainage facilities (3), and then constructing a composite foundation pile foundation (1); Step S23: laying a geotextile, then constructing an anti-seepage layer (5) on top of the geotextile, and at the same time constructing a first height section of a sea mud solidification wall (2) around the reservoir area; Step S24: laying geomembrane (6) and geotextile in the reservoir area, and constructing a leachate diversion layer (8) and leachate drainage facilities.

2. The method for constructing a fly ash landfill area on an offshore large deformation ultra-soft soil foundation according to claim 1 is characterized in that: The step S4 specifically comprises: backfilling soil around the reservoir area, and constructing the second height section of the sea mud solidification wall (2) and the wall geomembrane around the reservoir area.

3. The method for constructing a fly ash landfill area on an offshore large deformation ultra-soft soil foundation according to claim 2 is characterized in that: The anti-seepage layer (5) in step S23 is composed of solidified sea mud.

4. The method for constructing a fly ash landfill area on an offshore large deformation ultra-soft soil foundation according to claim 3 is characterized in that: The leachate drainage facility in step S24 comprises a leachate drainage pipe (9).

5. The method for constructing a fly ash landfill area on an offshore large deformation ultra-soft soil foundation according to claim 1 or 3, characterized in that: The geotextile in step S23 is laid on top of the drainage cushion layer (4).

6. A method for constructing a fly ash landfill area on an offshore large deformation ultra-soft soil foundation according to claim 1 or 4, characterized in that: In the step S24, the geomembrane (6) in the reservoir area is laid above the anti-seepage layer (5).

7. The method for constructing a fly ash landfill area on an offshore large deformation ultra-soft soil foundation according to claim 2 is characterized in that: The materials used for the backfill construction in step S21 and step S4 are all abandoned soil, and the backfill construction eventually forms a fill layer (7).

8. The method for constructing a fly ash landfill area on an offshore large deformation ultra-soft soil foundation according to claim 1 is characterized in that: The landfill materials in step S3 and step S5 are all solidified fly ash bags.

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