Rigid pipe ditch backfilling method and pipe ditch backfilling structure thereof

Abstract

The invention discloses a rigid pipe ditch backfilling method and a pipe ditch backfilling structure thereof, and belongs to the technical field of pipe ditch backfilling, and the method comprises the following steps: pre-determining the thickness of a foundation layer according to the designed rigid pipe diameter, the load borne by the pipe and the soil condition at the bottom of the pipe ditch; a rigid pipe is positioned and fixedly installed on the base layer, and high-strength flow-state solidified soil is backfilled and poured layer by layer step by step so that the stable layer can at least wrap a part of the rigid pipe from bottom to top and reach the determined stable layer pouring thickness; and on the basis of the settlement shrinkage coefficient of the high-density flow-state solidified soil and according to the predetermined thickness higher than the pipe ditch ground thickness during one-time continuous pouring and the lowest strength of the high-density flow-state solidified soil, a backfill layer is formed by adopting one-time continuous pouring of the high-density flow-state solidified soil. According to the rigid pipe ditch backfilling method and the pipe ditch backfilling structure thereof, the pipe ditch backfilling quality is improved, the stability and safety of the rigid pipe in the using process are ensured, the service life of the pipe is prolonged, and the maintenance cost is reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of pipe trench backfilling, and in particular relates to a rigid pipe trench backfilling method and a pipe trench backfilling structure. Background Art

[0002] In infrastructure construction, rigid pipes are widely used in many fields such as water supply, drainage, and gas transmission. The quality of trench backfill is directly related to the service life and operation safety of the pipeline. However, there are many problems with the traditional trench backfill method, such as unstable backfill material performance and unreasonable backfill process, which lead to the phenomenon of settlement, deformation and even rupture of the pipeline during use, which seriously affects the normal operation of the pipeline system and increases maintenance costs and safety hazards. Summary of the invention

[0003] The purpose of the present invention is to overcome the deficiencies in the prior art and provide a rigid pipe trench backfilling method and a trench backfilling structure thereof, which effectively solves the problems existing in the traditional backfilling method by adopting high-performance fluidized solidified soil materials and optimizing the backfilling process, improves the trench backfilling quality, ensures the stability and safety of the rigid pipe during use, prolongs the service life of the pipeline, and reduces maintenance costs.

[0004] To achieve the above object, the present invention is implemented by adopting the following technical solutions.

[0005] In one aspect, the present invention provides a method for backfilling a rigid pipe trench, comprising the following steps:

[0006] Step S1: predetermine the thickness of the foundation layer according to the designed rigid pipe diameter, the load borne by the pipe and the soil conditions at the bottom of the trench, and pour a foundation layer with a strength not less than a specific concrete grade at the bottom of the trench according to the determined foundation layer thickness;

[0007] Step S2: Positioning and fixing the rigid pipe on the foundation layer, predetermining the pouring thickness of the stabilization layer according to the pipe and the high-strength fluidized solidified soil, and gradually backfilling and pouring the high-strength fluidized solidified soil in layers so that the stabilization layer at least wraps a part of the rigid pipe from bottom to top and reaches the determined pouring thickness of the stabilization layer;

[0008] Step S3: Based on the settlement shrinkage coefficient of the high-density fluidized solidified soil and the predetermined thickness of the ground in the trench and the minimum strength of the high-density fluidized solidified soil during one continuous pouring, a backfill layer is formed by one continuous pouring of the high-density fluidized solidified soil.

[0009] Furthermore, the high-strength fluidized solidified soil of the stabilizing layer is composed of 60%-70% of high-quality raw soil, 10%-15% of high-efficiency solidifying agent, 0.5%-1% of reinforcing fiber material and 15%-20% of water;

[0010] The wet density of the high-strength fluidized solidified soil is controlled at 1600-1800 kg / m 3 The fluidity is maintained at 200±20mm to achieve self-leveling and self-compacting, the water seepage rate does not exceed 3% to ensure a dense and uniform structure, and the unconfined compressive strength after 28 days is above 5MPa.

[0011] Furthermore, the high-density fluidized solidified soil of the backfill layer is composed of 50%-70% raw soil, 10%-20% curing agent, 5%-15% admixture, 0.5%-2% additive and 10%-20% water to improve the bearing capacity of the foundation;

[0012] The wet density of the high-density fluidized solidified soil is 1800-2200 kg / m 3 The fluidity is maintained at 150±20mm to achieve self-leveling and self-compacting, the water seepage rate is controlled within 2% to maintain uniformity, the unconfined compressive strength is above 3MPa after 7 days, and above 8MPa after 28 days.

[0013] Furthermore, the thickness of the foundation layer and the compression deformation ΔL are determined in advance according to the designed rigid pipe diameter, the load borne by the pipe and the soil conditions at the bottom of the trench. The compression deformation ΔL refers to the deformation of the material or soil in the vertical direction under a certain pressure, which generally does not exceed 1%-2% of the pipe diameter, otherwise it will affect the rigid pipe; wherein, the formula for calculating the compression deformation ΔL from the foundation layer thickness L is expressed as:

[0014]

[0015] In the formula, L represents the thickness of the base layer, EA represents the tensile and compressive stiffness, and F 管 Indicates the pressure of the rigid pipe on the foundation layer, F 土 It indicates the pressure exerted by the upper fluidized solidified soil on the foundation layer.

[0016] Furthermore, the pouring thickness H of the stabilization layer is predetermined according to the pipeline and the high-strength fluidized solidified soil, and the formula is expressed as:

[0017]

[0018] Where R is the outer radius of the pipe; d is the thickness of the pipe; ρ 管 represents the rigid pipe density, ρ 流 represents the wet density of high-strength fluidized soil, k w Indicates the anti-floating safety factor.

[0019] Furthermore, based on the settlement shrinkage coefficient of high-density fluidized solidified soil and the predetermined minimum strength of the trench ground thickness and high-density fluidized solidified soil during one continuous pouring, the formula is expressed as:

[0020] During one continuous pouring, the thickness should be higher than the trench ground surface Δh:

[0021]

[0022] The minimum strength q of high-density fluidized solidified soil;

[0023]

[0024] Where K represents the safety factor, α represents the construction process correction factor, and β represents the strength reduction factor.

[0025] Furthermore, the high-strength fluidized solidified soil of the stabilizing layer is gradually poured in layers and blocks. During the pouring operation, the two sides of the rigid pipe should be symmetrically backfilled and compacted. After the high-strength fluidized solidified soil is consolidated, the next layer is poured. During pouring, attention is paid to fluidity and pouring speed. The pouring height difference is not greater than 1m, until the predetermined pouring thickness of the stabilizing layer is reached after consolidation.

[0026] Furthermore, in step S3, it also includes:

[0027] The backfill layer is made of high-density fluidized solidified soil and is poured once by pumping or chute pouring. Based on the shrinkage of the fluidized solidified soil, a high-density fluidized solidified soil with a thickness of Δh should be poured once continuously.

[0028] Provide support on both sides of the trench and the support height above the horizontal ground is greater than Δh thickness;

[0029] After pouring the backfill layer and the top layer of the fill body, the surface of the trench fill body should be immediately covered with plastic film or geotextile for moisturizing and curing. The curing time should be no less than 7 days. After the high-density fluidized solidified soil is consolidated and cured, the consolidated fluidized solidified soil above the ground should be cleaned up at one time with a bulldozer.

[0030] Furthermore, the concrete strength grade of the foundation layer is not less than C15;

[0031] If the rigid pipe is a small pipe with a diameter less than 600 mm, the thickness of the base layer is between 100 mm and 200 mm; if the rigid pipe is a large pipe with a diameter greater than 600 mm, the thickness of the base layer is between 300 mm and 500 mm.

[0032] In a second aspect, the present invention provides a rigid pipe trench backfill structure, comprising a foundation layer, a rigid pipe, a stabilizing layer and a backfill layer, which are backfilled and cast in layers from bottom to top from the bottom of the trench;

[0033] The foundation layer is arranged at the bottom of the trench, and the thickness of the foundation layer is determined according to the diameter of the rigid pipe, the load borne by the pipe and the soil conditions at the bottom of the trench, and is poured with a strength not lower than a specific concrete grade;

[0034] The rigid tube is positioned and fixed on the base layer;

[0035] The stabilizing layer is configured to determine the casting thickness of the stabilizing layer according to the rigid pipe and the high-strength fluidized solidified soil, and to gradually backfill and cast the high-strength fluidized solidified soil in layers so that the stabilizing layer at least wraps a portion of the rigid pipe from bottom to top and reaches the determined casting thickness of the stabilizing layer;

[0036] The backfill layer is poured on the stabilizing layer and the rigid pipe, and is higher than the preset thickness of the trench ground through one continuous pouring of high-density fluidized solidified soil and is flush with the horizontal bottom surface of the trench after the high-density fluidized solidified soil settles and shrinks.

[0037] Compared with the prior art, the beneficial effects achieved by the present invention are as follows: the rigid pipe trench backfilling method and trench backfilling structure provided by the present invention, the concrete foundation of the pipe bottom foundation layer provides a stable support for the pipeline construction to prevent displacement and settlement; the stable layer is backfilled with high-strength fluidized solidified soil according to the anti-floating formula combined with the site requirements, and the backfill height is accurately determined (the backfill pouring height of the fluidized solidified soil is determined) to achieve pipeline anti-floating; the backfill layer is backfilled taking into account the final settlement of the high-density fluidized solidified soil, and the high-density fluidized solidified soil with a thickness of Δh above the ground poured on site is determined by calculation (the height above the ground is determined to prepare for later settlement), so that one-time pouring can meet the backfilling requirements; by adopting high-performance fluidized solidified soil materials and optimized backfilling technology, the trench backfilling quality is improved, the stability and safety of the rigid pipe during use are ensured, the service life of the pipeline is extended, and the maintenance cost is reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 Flow chart of the rigid pipe trench backfill method.

[0039] Figure 2 Schematic diagram of the rigid pipe trench backfill structure.

[0040] In the figure:

[0041] 1. Base layer; 2. Rigid pipe: 3. Stabilization layer; 4. Backfill layer. DETAILED DESCRIPTION

[0042] The present invention will be further described below in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and cannot be used to limit the protection scope of the present invention.

[0043] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and the like are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, features defined as "first", "second", and the like may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0044] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood by specific circumstances.

[0045] Example

[0046] like Figure 1 As shown, an embodiment of the present invention provides a method for backfilling a rigid pipe trench, comprising the following steps:

[0047] Step S1: predetermine the thickness of the foundation layer according to the designed rigid pipe diameter, the load borne by the pipe and the soil conditions at the bottom of the trench, and pour a foundation layer with a strength not less than a specific concrete grade at the bottom of the trench according to the determined foundation layer thickness;

[0048] Step S2: Positioning and fixing the rigid pipe on the foundation layer, predetermining the pouring thickness of the stabilization layer according to the pipe and the high-strength fluidized solidified soil, and gradually backfilling and pouring the high-strength fluidized solidified soil in layers so that the stabilization layer at least wraps a part of the rigid pipe from bottom to top and reaches the determined pouring thickness of the stabilization layer;

[0049] Step S3: Based on the settlement shrinkage coefficient of the high-density fluidized solidified soil and the predetermined thickness of the ground in the trench and the minimum strength of the high-density fluidized solidified soil during one continuous pouring, a backfill layer is formed by one continuous pouring of the high-density fluidized solidified soil.

[0050] In this embodiment, vibration is performed during backfilling to make the solidified soil more compact, reduce the void ratio, and improve its bearing capacity. An insertable vibrating rod or a flat vibrator can be used, and a suitable vibrating device can be selected according to the backfill position and the fluidity of the solidified soil.

[0051] like Figure 2 As shown, an embodiment of the present invention provides a rigid pipe trench backfill structure, including a foundation layer, a rigid pipe, a stabilizing layer and a backfill layer which are backfilled and cast in layers from the bottom of the trench upward;

[0052] The foundation layer is arranged at the bottom of the trench. The thickness of the foundation layer is determined according to the diameter of the rigid pipe, the load borne by the pipe and the soil conditions at the bottom of the trench, and the concrete is poured with a strength not lower than the specific concrete grade;

[0053] Rigid pipe, positioned and fixed on the base layer;

[0054] The stabilizing layer is configured to determine the pouring thickness of the stabilizing layer according to the rigid pipe and the high-strength fluidized solidified soil, and the high-strength fluidized solidified soil is backfilled and poured in layers so that the stabilizing layer at least wraps a part of the rigid pipe from bottom to top and reaches the determined pouring thickness of the stabilizing layer;

[0055] The backfill layer is poured on the stabilizing layer and the rigid pipe. After one continuous pouring of high-density fluidized solidified soil, the backfill is higher than the preset thickness of the trench ground and is flush with the horizontal bottom surface of the trench after the high-density fluidized solidified soil settles and shrinks.

[0056] In this embodiment, the high-strength fluidized solidified soil of the stabilization layer is composed of 60%-70% high-quality raw soil, 10%-15% high-efficiency solidifying agent, 0.5%-1% reinforcing fiber material and 15%-20% water, as shown in Table 1.

[0057] Table 1 assumes that 1m 3 High strength fluidized soil

[0058]

[0059] The wet density of high-strength fluidized solidified soil is controlled at 1600-1800kg / m 3 The fluidity is maintained at 200±20mm to achieve self-leveling and self-compacting, the water seepage rate does not exceed 3% to ensure a dense and uniform structure, and the unconfined compressive strength after 28 days is above 5MPa.

[0060] The high-density fluidized solidified soil of the backfill layer is composed of 50%-70% raw soil, 10%-20% curing agent, 5%-15% admixture, 0.5%-2% additive and 10%-20% water to improve the bearing capacity of the foundation, as shown in Table 2.

[0061] Assume that you want to prepare 1m 3 High density fluidized soil

[0062]

[0063] The wet density of high-density fluidized solidified soil is 1800-2200kg / m 3 The fluidity is maintained at 150±20mm to achieve self-leveling and self-compacting, the water seepage rate is controlled within 2% to maintain uniformity, the unconfined compressive strength is above 3MPa after 7 days, and above 8MPa after 28 days.

[0064] In this embodiment, in addition to fly ash and slag, some industrial waste materials such as steel slag, red mud, etc. can also be used as admixtures. Steel slag contains relatively high active ingredients, such as calcium oxide, silicon dioxide, etc., which can react with the curing agent to improve the strength of the solidified soil. Red mud is a polluting waste residue discharged when the aluminum industry extracts alumina. Its rational use can not only reduce the cost of solidified soil, but also reduce environmental pollution.

[0065] The thickness of the foundation layer is determined in advance according to the designed rigid pipe diameter, the load borne by the pipe and the soil conditions at the bottom of the trench. ΔL refers to the deformation of the material or soil in the vertical direction under a certain pressure, which generally does not exceed 1%-2% of the pipe diameter, otherwise it will affect the rigid pipe; the formula for calculating the compression deformation ΔL from the foundation layer thickness L is expressed as:

[0066]

[0067] In the formula, L represents the thickness of the base layer, EA represents the tensile and compressive stiffness, and F 管 Indicates the pressure of the rigid pipe on the base layer, F 土 It indicates the pressure exerted by the upper fluidized solidified soil on the foundation layer.

[0068] The pouring thickness H of the stabilization layer is determined in advance according to the pipeline and high-strength fluidized solidified soil. The formula is expressed as:

[0069]

[0070] Where R is the outer radius of the pipe; d is the thickness of the pipe; ρ 管 represents the rigid pipe density, ρ 流 represents the wet density of high-strength fluidized soil, k w Indicates the anti-floating safety factor.

[0071] Based on the settlement shrinkage coefficient of high-density fluidized solidified soil and the predetermined minimum strength of the trench ground and high-density fluidized solidified soil during one continuous pouring, the formula is:

[0072] During one continuous pouring, the thickness should be higher than the trench ground surface Δh:

[0073]

[0074] The minimum strength q of high-density fluidized solidified soil;

[0075]

[0076] Where K represents the safety factor, α represents the construction process correction factor, and β represents the strength reduction factor.

[0077] In this embodiment, high-strength fluidized solidified soil is used when backfilling the stable layer. Since the pipeline will float after one backfill, it needs to be backfilled according to the anti-floating requirements. The backfill thickness is determined based on the pipeline, fluidized solidified soil and site requirements combined with the anti-floating formula. High-strength fluidized solidified soil should be poured in layers and blocks. The pouring operation should be carried out symmetrically, and the layers should be backfilled densely. After the fluidized solidified soil is consolidated, the next layer should be poured. During pouring, attention should be paid to fluidity and pouring speed. The pouring height difference should not be greater than 1m, until the predetermined stable layer pouring thickness is reached after consolidation to reduce the pressure on the pipeline and ensure that the pipeline does not move.

[0078] In this embodiment, step S3 further includes:

[0079] The backfill layer is made of high-density fluidized solidified soil and poured once by pumping or chute. Based on the shrinkage of fluidized solidified soil, a continuous pouring construction should be adopted, and a high-density fluidized solidified soil with a thickness of Δh should be poured more;

[0080] Provide support on both sides of the trench and the support height above the horizontal ground is greater than Δh thickness;

[0081] After pouring the backfill layer and the top layer of the fill body, the surface of the trench fill body should be immediately covered with plastic film or geotextile for moisturizing and curing. The curing time should be no less than 7 days. After the high-density fluidized solidified soil is consolidated and cured, the consolidated fluidized solidified soil above the ground should be cleaned up at one time with a bulldozer.

[0082] In this embodiment, the rigid pipes such as concrete materials are laid, and backfilled in layers from the bottom of the trench. The thickness of the base layer is usually determined according to the diameter of the pipe, the load on the pipe, and the soil conditions. Concrete of the same grade as the pipe foundation is usually used for backfilling. The density of the backfill material needs to be ensured to prevent uneven settlement of the pipe. The specific thickness needs to be determined according to local building codes and engineering requirements, and the concrete strength grade is not less than C15 concrete.

[0083] When laying pipes made of concrete materials, backfilling is done in layers from the bottom of the trench. The thickness of the base layer is usually determined based on the diameter of the pipe, the load on the pipe, and soil conditions. If the rigid pipe is a small pipe with a diameter less than 600mm, the thickness of the base layer is between 100mm and 200mm; if the rigid pipe is a large pipe with a diameter greater than 600mm, the thickness of the base layer is between 300mm and 500mm.

[0084] Next, the working principle of the concrete micro-crack detection system of the present invention is described in combination with the operation of a specific embodiment.

[0085] The trench bottom is 1m wide and 1.8m deep. The concrete sewage pipe has an outer diameter of 600mm, a wall thickness of 60mm, and a density of 2400kg / m 3 The density of high-strength fluidized solidified soil is 1600kg / m3, and the concrete of the foundation layer at the bottom of the pipe is C20.

[0086] (1) The foundation layer at the bottom of the pipe is backfilled with 200 mm of C20 concrete and brought into the numerical calculation.

[0087]

[0088] The calculated compression deformation of the foundation layer concrete is 0.00661mm.

[0089] 600×1%=6mm>ΔL

[0090] The compression deformation of the base layer will not cause damage to the concrete pipe

[0091] (2) The stable layer is brought into the numerical calculation.

[0092]

[0093] H≈260mm, and high-strength fluidized solidified soil is backfilled 260mm on both sides of the pipeline.

[0094] (3) The backfill thickness of the backfill layer is 1340 mm, the wet density is 1800 kg / m3, and the shrinkage rate of the high-density fluidized solidified soil is 3%. Under non-standard curing, the shrinkage coefficient a is taken as 0.0002 and substituted into the formula:

[0095]

[0096] So Δh=40mm,

[0097] 1340+40+0.00661=1380.00661mm

[0098] The actual backfill height is 1380.00661mm.

[0099] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for backfilling a rigid pipe trench, characterized in that: The steps include: Step S1: predetermine the thickness of the foundation layer according to the designed rigid pipe diameter, the load borne by the pipe and the soil conditions at the bottom of the trench, and pour a foundation layer with a strength not less than a specific concrete grade at the bottom of the trench according to the determined foundation layer thickness; Step S2: Positioning and fixing the rigid pipe on the foundation layer, predetermining the pouring thickness of the stabilization layer according to the pipe and the high-strength fluidized solidified soil, and gradually backfilling and pouring the high-strength fluidized solidified soil in layers so that the stabilization layer at least wraps a part of the rigid pipe from bottom to top and reaches the determined pouring thickness of the stabilization layer; Step S3: Based on the settlement shrinkage coefficient of the high-density fluidized solidified soil and the predetermined thickness of the ground in the trench and the minimum strength of the high-density fluidized solidified soil during one continuous pouring, a backfill layer is formed by one continuous pouring of the high-density fluidized solidified soil.

2. The method for backfilling a rigid pipe trench according to claim 1, characterized in that: The high-strength fluidized solidified soil of the stabilizing layer is composed of 60%-70% high-quality raw soil, 10%-15% high-efficiency solidifying agent, 0.5%-1% reinforcing fiber material and 15%-20% water; The wet density of the high-strength fluidized solidified soil is controlled at 1600-1800 kg / m 3 The fluidity is maintained at 200±20mm to achieve self-leveling and self-compacting, the water seepage rate does not exceed 3% to ensure a dense and uniform structure, and the unconfined compressive strength after 28 days is above 5MPa.

3. The rigid pipe trench backfilling method according to claim 2, characterized in that: The high-density fluidized solidified soil of the backfill layer is composed of 50%-70% raw soil, 10%-20% curing agent, 5%-15% admixture, 0.5%-2% additive and 10%-20% water to improve the bearing capacity of the foundation; The wet density of the high-density fluidized solidified soil is 1800-2200 kg / m 3 The fluidity is maintained at 150±20mm to achieve self-leveling and self-compacting, the water seepage rate is controlled within 2% to maintain uniformity, the unconfined compressive strength is above 3MPa after 7 days, and above 8MPa after 28 days.

4. The method for backfilling a rigid pipe trench according to claim 3, characterized in that: The thickness of the foundation layer and the compression deformation ΔL are determined in advance according to the designed rigid pipe diameter, the load borne by the pipe and the soil conditions at the bottom of the trench. The compression deformation ΔL generally does not exceed 1%-2% of the pipe diameter. The formula for calculating the compression deformation ΔL from the foundation layer thickness L is expressed as: In the formula, L represents the thickness of the base layer, EA represents the tensile and compressive stiffness, and F 管 Indicates the pressure of the rigid pipe on the base layer, F 土 It indicates the pressure exerted by the upper fluidized solidified soil on the foundation layer.

5. The rigid pipe trench backfilling method according to claim 4, characterized in that: The pouring thickness H of the stabilization layer is determined in advance according to the pipeline and high-strength fluidized solidified soil. The formula is expressed as: Where R is the outer radius of the pipe; d is the thickness of the pipe; ρ 管 represents the rigid pipe density, ρ 流 represents the wet density of high-strength fluidized soil, k w Indicates the anti-floating safety factor.

6. The method for backfilling a rigid pipe trench according to claim 5, characterized in that: Based on the settlement shrinkage coefficient of high-density fluidized solidified soil and the predetermined minimum strength of the trench ground and high-density fluidized solidified soil during one continuous pouring, the formula is: During one continuous pouring, the thickness should be higher than the trench ground surface Δh: The minimum strength q of high-density fluidized solidified soil; Where K represents the safety factor, α represents the construction process correction factor, and β represents the strength reduction factor.

7. The method for backfilling a rigid pipe trench according to claim 6, characterized in that: The high-strength fluidized solidified soil of the stabilizing layer is gradually poured in layers and blocks. During the pouring operation, the two sides of the rigid pipe should be symmetrically backfilled and compacted. After the high-strength fluidized solidified soil is consolidated, the next layer is poured. During pouring, attention is paid to fluidity and pouring speed. The pouring height difference is not greater than 1m, until the predetermined pouring thickness of the stabilizing layer is reached after consolidation.

8. The method for backfilling a rigid pipe trench according to claim 7, characterized in that: In step S3, it also includes: The backfill layer is made of high-density fluidized solidified soil and is poured once by pumping or chute pouring. Based on the shrinkage of the fluidized solidified soil, a high-density fluidized solidified soil with a thickness of Δh should be poured once continuously. Provide support on both sides of the trench and the support height above the horizontal ground is greater than Δh thickness; After pouring the backfill layer and the top layer of the fill body, the surface of the trench fill body should be immediately covered with plastic film or geotextile for moisturizing and curing. The curing time should be no less than 7 days. After the high-density fluidized solidified soil is consolidated and cured, the consolidated fluidized solidified soil above the ground should be cleaned up at one time with a bulldozer.

9. The method for backfilling a rigid pipe trench according to claim 1, characterized in that: The concrete strength grade of the foundation layer is not less than C15; If the rigid pipe is a small pipe with a diameter less than 600 mm, the thickness of the base layer is between 100 mm and 200 mm; if the rigid pipe is a large pipe with a diameter greater than 600 mm, the thickness of the base layer is between 300 mm and 500 mm.

10. A rigid pipe trench backfill structure, characterized in that: It includes a foundation layer, a rigid pipe, a stabilizing layer and a backfill layer which are backfilled and poured in layers from the bottom of the trench upward; The foundation layer is arranged at the bottom of the trench, and the thickness of the foundation layer is determined according to the diameter of the rigid pipe, the load borne by the pipe and the soil conditions at the bottom of the trench, and is poured with a strength not lower than a specific concrete grade; The rigid tube is positioned and fixed on the base layer; The stabilizing layer is configured to determine the casting thickness of the stabilizing layer according to the rigid pipe and the high-strength fluidized solidified soil, and to gradually backfill and cast the high-strength fluidized solidified soil in layers so that the stabilizing layer at least wraps a portion of the rigid pipe from bottom to top and reaches the determined casting thickness of the stabilizing layer; The backfill layer is poured on the stabilizing layer and the rigid pipe, and is higher than the preset thickness of the trench ground through one continuous pouring of high-density fluidized solidified soil and is flush with the horizontal bottom surface of the trench after the high-density fluidized solidified soil settles and shrinks.

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