CN111501807A - Large-pipe-diameter pipe laying structure in collapsible loess area and construction method - Google Patents

Abstract

The invention discloses a large-pipe-diameter pipe laying structure in a collapsible loess area, and belongs to the technical field of municipal engineering or hydraulic engineering. Comprises an embedded pipe, a drainage ditch, a water seepage well, a longitudinal curtain, a transverse curtain, a rolling cushion layer, a sleeve valve pipe, a grouting material layer and a paving layer. A construction method for a large-diameter buried pipe laying structure in a collapsible loess area comprises the steps of forming a vertical isolation strip in a foundation below a buried pipe by adopting a longitudinal curtain and a transverse curtain, pouring grouting materials into sleeve valve pipes under the foundation, forming a grouting material layer at the bottom of the foundation, laying a laying cover layer on the foundation at the top of the curtain, sequentially laying a rolling cushion layer on the laying cover layer, rolling two sides of the rolling cushion layer to dig drainage ditches, arranging seepage wells in the drainage ditches at intervals, laying an anti-seepage film, throwing pervious aggregates in the drainage ditches and the seepage wells, finally laying the buried pipe above the anti-seepage film, and backfilling the pipe ditches. The invention has simple process, environmental protection, high construction speed and good economic and social benefits.

Description

Large-pipe-diameter pipe laying structure in collapsible loess area and construction method

Technical Field

The invention belongs to the technical field of municipal engineering or water conservancy engineering, and particularly relates to a large-pipe-diameter buried pipe laying structure and a construction method in a collapsible loess area.

Background

Collapsible loess is widely distributed in wide areas of Shanxi, Shaanxi, inner Mongolia, Gansu provinces and other provinces of China. Collapsible loess includes self-weight collapsible loess and non-self-weight collapsible loess, collectively referred to as collapsible loess. After the collapsible loess is soaked in water, the soil structure is damaged, so that the soil is obviously additionally sunk, and the building is unevenly sunk or collapsed. When laying the pipe laying in collapsible loess area, if the ground is handled improperly, can make the pipe laying produce inhomogeneous settlement to change the stress state of pipe laying, threaten the operation safety of pipeline.

At present, with the demand of industrialized construction and development in China, the engineering projects for laying pipelines in collapsible loess areas are increasing day by day. When the diameter of the directly buried pipe is smaller, the collapsible loess foundation can be generally not treated or only the collapsible amount is partially eliminated, and the waterproof measure and the structural measure are considered to be adopted to make up the defect of foundation treatment. However, when the diameter of the directly buried pipe is large, the bearing capacity of the foundation is required to be high due to the large weight of the pipe itself and the liquid in the pipe, and the construction of the large-diameter pipe becomes a complicated system engineering.

When the pipe burying ditch is subjected to basic treatment, the effect of the pipe burying ditch basic treatment is that the macroporous structure of collapsible loess is damaged, so that the collapsible property of the foundation is eliminated, and the occurrence of the loess collapsible phenomenon is fundamentally avoided or weakened. At present, a plurality of methods for pipeline foundation treatment are available, and the common methods comprise the following steps: soil or lime soil bedding method, pre-soaking water treatment method, heavy hammer tamping method, pile foundation method and the like. Each treatment method has its application range, limitations and their respective advantages and disadvantages.

The soil or lime soil cushion method is to dig out the collapsible soil layer under the pipe ditch and tamp or compact the clay or lime soil taken out. Its advantages are simple construction and high effect. The large pore structure of the compacted loess is destroyed, the pores are reduced, the compactness of the soil is increased, and the collapsibility of the loess within the thickness of the cushion layer can be eliminated by the method.

The pre-soaking treatment method is characterized in that the characteristic that self-weight subsidence occurs after loess is soaked in water is utilized, and large-area soaking is carried out in a pit before construction, so that the soil body is subjected to self-weight subsidence, and the aim of compacting collapsible loess is fulfilled.

The heavy hammer tamping method is also called as a dynamic compaction method, has better effect on strengthening the collapsible loess foundation, and can be used for treating the buried pipe foundation by the dynamic compaction method under the conditions that the collapsible loess layer is thicker, the collapsible deformation is large, the self weight of the pipeline is heavy (such as a prestressed reinforced concrete water supply pipe and a reinforced concrete drain pipe) and the requirement on the safety of the pipeline is high in pipeline construction. The construction process is that after the pipe trench is dug, if collapsible loess is tamped tightly by a heavy hammer repeatedly in the state of optimal water content, the collapsible property can be eliminated in the effective tamping thickness range, the compressibility is reduced, and a weakly permeable layer for reducing the surface water infiltration is formed. The method has the advantages of remarkable effect, simple equipment, material saving, short construction period and the like when used for treating the collapsible loess foundation, so that the method is frequently adopted in a plurality of large-pipe-diameter pipe laying projects, and a good effect is obtained in practice.

The pile foundation method can be divided into concrete piles, steel piles, composite material piles and the like according to the pile body materials. Its advantages are high bearing capacity of foundation, obvious defects, and high construction cost. Therefore, for the foundation of the large-diameter buried pipe, which is a relatively high-rise building foundation, the requirement on the bearing capacity is not particularly high, but the foundation with higher requirement on the construction period is obviously not applicable.

For large-diameter underground pipe burying in a collapsible loess area, the foundation treatment effects of the soil or lime soil cushion method and the pre-soaking water treatment method are poor, after the foundation treatment is carried out by the two methods, the collapsible settlement phenomenon of the pipe burying foundation can not be completely eliminated, and engineering accidents such as uneven pipe burying settlement and the like still occur after the foundation treatment; the heavy hammer tamping method and the pile foundation method have good foundation treatment effect, but in the foundation treatment process, the heavy hammer tamping method needs a larger construction field, and has larger influence on the surrounding environment during construction. The pile foundation principle has the disadvantages of complex construction process, higher construction cost, longer construction period and the like. In summary, the common foundation treatment methods are not suitable for the engineering projects with strict requirements on construction cost and construction period, such as long-distance and large-pipe-diameter pipe-burying engineering in collapsible loess areas. Therefore, the current practical engineering problem of laying the large-diameter buried pipes in the collapsible loess area in a long distance is urgent to research and develop a novel foundation treatment structure suitable for laying the large-diameter buried pipes in the collapsible loess area.

Disclosure of Invention

Technical problem

After laying for overcoming current collapsible loess area big pipe diameter pipe laying, because of the collapsible loess of pipe laying below meeting water the back, the yellow soil collapsible settlement phenomenon easily takes place for pipe laying base in pipe laying department, and then leads to taking place inhomogeneous the subsidence for pipe laying base in the pipe ditch to make the pipe laying often take place the technical problem of accidents such as fracture, leaking. The invention aims to solve the technical problem by means of measures such as technical improvement and the like.

Technical scheme

In order to solve the technical problem, the invention adopts the following technical scheme:

the utility model provides a large pipe diameter pipe laying structure in collapsible loess area, includes: the device comprises an embedded pipe, a drainage ditch, a water seepage well, a longitudinal curtain, a transverse curtain, a rolling cushion layer, a sleeve valve pipe, a grouting material layer and a cover layer, wherein an arc-shaped groove is formed in the rolling cushion layer, two sides of the arc-shaped groove are provided with downward slope surfaces, an anti-seepage film is paved on the slope surfaces, the drainage ditch is arranged at the lower end of the slope surfaces, the water seepage well is arranged in the middle of the drainage ditch at intervals, the longitudinal curtain and the transverse curtain are positioned in a pipe ditch foundation for pipe embedding excavation, the longitudinal curtain comprises a left longitudinal curtain and a right longitudinal curtain, the left longitudinal curtain and the right longitudinal curtain are continuously distributed along the axial direction of the embedded pipe, and the sleeve valve pipe and the transverse curtain are symmetrically arranged along the axis of the embedded pipe between the left longitudinal curtain and the right longitudinal curtain at intervals; the bottom of the left longitudinal curtain and the bottom of the right longitudinal curtain are connected through a grouting material layer, the lower end of the sleeve valve pipe extends into the grouting material layer, a plurality of grouting holes are formed in the lower end of the sleeve valve pipe, the covering layer is arranged on original loess between the left longitudinal curtain and the right longitudinal curtain, and the rolling cushion layer is arranged on the covering layer.

Preferably, the material of the rolling mat layer is a material with low water permeability, such as lime soil and/or clay.

Preferably, the material of the paving layer is a material with low water permeability, such as lime soil and/or clay.

Preferably, the material of the anti-seepage film is a chemical film made of materials such as polyvinyl chloride (PVC) and/or Polyethylene (PE) and/or EVA (ethylene/vinyl acetate copolymer).

Preferably, pervious aggregates are thrown in the drainage ditch and the water seepage well.

Preferably, the pervious aggregate is a recycled concrete aggregate and/or a common crushed stone aggregate and/or a high-permeability ore material such as coarse sand with good gradation.

Preferably, the rolling cushion further comprises a water collecting groove and a water guide pipe, the water collecting groove is arranged on the rolling cushion layer and between two adjacent buried pipes, the water guide pipe is arranged in the rolling cushion layer, two ends of the water guide pipe are respectively communicated with the drainage ditch and the water collecting groove, and the drainage ditch and the water collecting groove can be in a precast concrete form and/or a precast resin material form.

A construction method for a large-pipe-diameter buried pipe laying structure in a collapsible loess area is characterized by comprising the following steps of:

1) measuring and paying off operation, excavating the pipe trench base to the height of an excavated surface, and leveling the trench base;

2) and sequentially manufacturing a longitudinal curtain and a transverse curtain along the designed position of the bottom of the pipe ditch, inserting a sleeve valve pipe on the basis of the ditch bottom between the longitudinal curtains after all the curtains are manufactured, and filling grout into the ground base part through a plurality of grouting holes arranged at the lower end of the sleeve valve pipe, so that the bottoms of the longitudinal curtain and the transverse curtain are serially communicated by the grout.

3) And excavating partial trench bottom foundation soil layers at the tops of the longitudinal curtains and the transverse curtains below the height of the excavation surface according to the design excavation requirement.

4) And constructing a drainage ditch and a water seepage well on the outer side of the longitudinal curtain according to design requirements.

5) And constructing a paving layer on the tops of the longitudinal curtain and the transverse curtain.

6) And throwing and filling the pervious aggregate into the pervious wells and the drainage ditches.

7) And (5) rolling and filling the rolling cushion layer by layer according to the design requirement until the rolling cushion layer construction is finished.

8) And flattening the rolled cushion layer after construction, and paving an impermeable film on the rolled cushion layer.

9) And hoisting and installing the buried pipe, and connecting the adjacent pipe sections.

10) And backfilling the original soil, carrying out layered rolling, and completing construction after backfilling to the original ground elevation.

Principle of the technology

Known by the characteristic of collapsible loess, when collapsible loess trench basis met water and wet when infiltrating, the collapsible settlement phenomenon easily takes place for the loess of trench basis, and then leads to under the pipe laying basis to take place inhomogeneous settlement, under the dead weight effect of the backfill above the pipe laying, the pipe laying can take place engineering accidents such as fracture, seepage. When the buried pipe is leaked, the collapsible loess in the foundation below the buried pipe is corroded by the leaked water to generate obvious additional sinking, and the leakage and the damage of the buried pipe are further accelerated.

In engineering practice, generally, in order to ensure the safety and normal use of a pipeline on a collapsible loess foundation, foundation treatment must be carried out on a buried pipe lower foundation under most conditions, so that the subsidence of foundation soil is partially or completely eliminated, the bearing capacity of the foundation is improved, and accidents such as breakage and leakage of the buried pipe caused by uneven settlement of the buried pipe lower foundation are prevented.

Publicly known, the pipe laying engineering is mainly with eliminating or reducing its collapsible volume as the purpose through the regional engineering measure of collapsible loess, generally mostly through leading, stifled, filling etc. the mode of dredging surface water, avoids the pipeline to pass through regional soil body and soaks, to the foundation treatment of the regional pipe laying of collapsible loess, the general principle of foundation treatment is: the loess collapsibility is eliminated or partially eliminated by engineering measures. When the pipe burying ditch foundation is processed, the purpose of the treatment of the pipe ditch bottom foundation is to destroy the macroporous structure of collapsible loess so as to eliminate the collapsible property of the foundation and fundamentally avoid or weaken the occurrence of the loess collapsible phenomenon. The method for eliminating the collapsibility of the loess is various, and the prior engineering mainly adopts a soil body encryption method (such as a dynamic compaction method and a compacted lime-soil pile) and a soil body reinforcement method (such as a lime-soil cushion method) for treatment. The more commonly used methods are: soil or lime soil bedding method, pre-soaking water treatment method, heavy hammer tamping method, pile foundation method and the like. Various methods for treating the under-pipe foundation have application range, limitations and respective advantages and disadvantages. However, the above methods have the common features that: all carry out physical treatment with the loess of basic place department for the microstructure of basic place loess changes, thereby makes its collapsible nature reduce, has improved the bearing capacity of foundation under the pipe laying incidentally simultaneously.

The invention relates to a large-pipe-diameter buried pipe laying structure in a collapsible loess area and a construction method. After grouting is completed, cleaning a curtain top pipe ditch foundation, laying a paving layer, sequentially laying a rolling cushion layer above the paving layer, wherein the cross section of the rolling cushion layer is triangular, after rolling and laying of the rolling cushion layer are completed, drainage ditches are dug at the left side and the right side of the rolling cushion layer, seepage wells are arranged in the drainage ditches at intervals, then an anti-seepage film is laid, and after the anti-seepage film is laid, the anti-seepage aggregate is piled up and put in the drainage ditches and the seepage wells. And after the processes are finished, laying the buried pipe, and after the buried pipe is laid, rolling and backfilling the pipe ditch by using original soil.

① laying layer, transverse curtain, longitudinal curtain and grouting material at the bottom of the foundation form a plurality of closed waterproof cavities in space, on one hand, the bearing capacity of the bottom of the foundation can be improved, on the other hand, the bottom of the foundation can be isolated from external water, so that soil in the curtain is in a relatively isolated state, and thus the phenomenon of subsidence cannot occur, ② utilizes rolling cushion layer, impermeable film, drainage ditch and permeable well with triangular sections, when the soil above the buried pipe has the water seepage phenomenon, the water seepage flows into the permeable aggregate along the impermeable film, then the permeable aggregate continuously flows into the permeable well outside the longitudinal curtain, and the permeable aggregate directly permeates into the soil below the buried pipe based on the ① and ② points.

From the above analysis, the technical principle adopted by the invention is as follows: through switching over to prior art and moving usefulness for the buried pipe below soil body is isolated with ground precipitation, and this has directly stopped collapsible loess and has taken place the cause of "meeting water subsidence" rather than adopting the current publicly known-through the microstructure that changes basic department loess, thereby makes its collapsible nature reduce, increases the bearing capacity of foundation under the buried pipe incidentally simultaneously.

Advantageous effects

The large-pipe-diameter buried pipe laying structure and the construction method in the collapsible loess area are adopted. Can make common collapsible loess area in the engineering, its bearing capacity descends rapidly after the loess meets water, and then often leads to the probability greatly reduced that accidents such as big pipe diameter pipe laying took place to split, seepage. After the technical method is adopted, the buried pipe can stably and well run in the operation and maintenance period, and the later operation and maintenance cost of the buried pipe is greatly reduced. The invention also has the following beneficial effects: the materials and engineering machines involved in the implementation process of the invention are common materials and equipment, the process is simple, the construction scheme is green and environment-friendly, the construction speed is high, and good economic and social benefits can be obtained by adopting the large-pipe-diameter pipe-burying engineering.

Drawings

FIG. 1 is a schematic structural view of a large-caliber pipe laying structure in collapsible loess areas according to the present invention;

FIG. 2 is a cross-sectional view A-A of FIG. 1;

FIG. 3 is a cross-sectional view taken along line B-B of FIG. 1;

fig. 4 is a schematic structural diagram of the second embodiment.

Reference numerals: 1-pipe burying; 2-a drainage ditch; 3-a water seepage well; 41-longitudinal curtain; 410-left longitudinal curtain; 411-right longitudinal curtain; 42-transverse curtains; 5-rolling the cushion layer; 6-impermeable membrane; 7-sleeve valve tube; 8-grouting holes; 9-grouting a slurry layer; 10-paving a layer; 11-a pervious aggregate; 12-a water collecting tank; 13-water guiding pipe.

Detailed Description

The technical scheme of the invention is clearly and completely described below with reference to the accompanying drawings 1-4.

The first embodiment is as follows: in actual construction, as shown in fig. 1, firstly, a measurement and paying-off operation is performed, a pipe trench is excavated to the height of an excavated surface, the bottom of the trench is flat, construction operations of longitudinal curtains 41 and transverse curtains 42 are performed in a buried pipe trench foundation, 1 row of sleeve valve pipes 7 (shown in fig. 2) are arranged between the longitudinal curtains at intervals, and grouting holes 8 are formed in the lower ends of the sleeve valve pipes 7. After the curtain construction is finished, a vertical isolation strip is formed in the collapsible loess foundation below the buried pipe by the longitudinal curtain 41 and the transverse curtain 42, grouting materials are poured into the foundation of the ground through the sleeve valve pipe 7 and the grouting holes 8 on the sleeve valve pipe after the curtain construction and maintenance are finished, under the action of pressure, the grouting materials form an isolation layer, namely a grouting material layer 9, at the bottom of the foundation below the curtain, and the foundation in the curtain is isolated from the foundation below the curtain by the isolation layer. After grouting is finished, a pipe ditch foundation at the top of the curtain is cleaned and leveled, a paving layer 10 is laid, the plane position of the paving layer 10 covers the range surrounded by the longitudinal curtain 41 and the transverse curtain 42, the paving layer extends to the edge of a drainage ditch towards the outer side of the longitudinal curtain 41, the paving layer 10 is made of materials with extremely small water permeability such as clay, and the like, so that after the paving layer 10 is laid, grouting materials, the longitudinal curtain 41, the transverse curtain 42 and the paving layer 10 form a waterproof closed cavity (shown in attached figures 1-3) in space, the closed cavity can ensure that external seepage water cannot be immersed into the cavity, the original loess in the cavity is always in a relatively stable stress state, and the phenomenon of yellow soil wet subsidence is avoided because of no external seepage water. This is one of the creativity of the present invention.

After the paving layer 10 is paved, the rolling cushion layer 5 is paved above the paving layer in sequence, the cross section of the rolling cushion layer 5 is triangular, after the rolling cushion layer 5 is rolled and paved, drainage ditches 2 are dug at the left side and the right side of the rolling cushion layer 5, seepage wells 3 are arranged in the drainage ditches 2 at intervals, then the seepage-proof membranes 6 are paved, after the seepage-proof membranes 6 are paved, the water-permeable aggregates 11 are put in the seepage wells 3 until the bottom surfaces of the drainage ditches 2, and the water-permeable aggregates are piled in the drainage ditches 2. And after the working procedures are finished, laying the buried pipe 1, and after the buried pipe is laid, rolling and backfilling the pipe ditch by using original soil. After the backfilling is finished, the large-pipe-diameter pipe laying structure in the collapsible loess area is manufactured. For example, in the summer rainstorm weather, rainwater on the ground above the buried pipe 1 can seep to the bottom of the buried pipe along the backfill soil above the buried pipe, and then seepage water in the backfill soil can flow downstream along the slope of the impermeable membrane 6 to flow into the drainage ditches on two sides of the buried pipe 1, and further, the seepage water can penetrate through the permeable aggregate 11 and continuously flow into the seepage well 3, and then seep into soil on two sides of the longitudinal curtain 41 through the seepage well 3. The design of the laying structure directly prevents rainwater on the ground surface of the buried pipe foundation from directly permeating into the foundation soil body below the buried pipe, and the probability of the loess collapsible settlement phenomenon is correspondingly reduced because the probability of water seepage in the foundation soil body below the buried pipe is greatly reduced, which is the second creative aspect of the invention.

Example two: as shown in fig. 4, in an actual project, sometimes, the buried pipe 1 is designed to be 2 or 3 or more parallel pipes according to the actual needs of the project, at this time, the large-diameter buried pipe laying structure in a collapsible loess area of the present invention needs only to be changed slightly, which is similar to the buried pipe laying structure in fig. 1, at this time, pipe trench excavation is still performed first, after the excavation reaches the excavation surface level, a longitudinal curtain 41 and a transverse curtain 42 are arranged in the pipe trench foundation of the buried pipe 1, after the curtain construction is completed, a vertical isolation strip is formed in the collapsible loess foundation below the buried pipe, then a plurality of rows of sleeve valve pipes 7 are arranged between the left and right longitudinal curtains 41, each row of sleeve valve pipes 7 are distributed at longitudinal intervals, after all the sleeve valve pipes 7 are arranged, grouting material is poured into the foundation through grouting holes 8 on the sleeve valve pipes 7, and under the pressure, the grouting material forms an isolation layer at the bottom of the foundation below the curtain, which isolates the inner base of the curtain from the lower base of the curtain. After grouting is completed, cleaning a pipe ditch foundation at the top of a curtain, laying a paving layer 10, laying a rolling cushion layer 5 above the paving layer 10 in sequence, wherein the cross section of the rolling cushion layer 5 is triangular, laying water guide pipes 13 according to the drawing requirements when the rolling cushion layer 5 is laid, paying attention to the inclination angle of the water guide pipes 13 when the water guide pipes 13 are laid, installing a water collection groove 12 and reliably connecting the water guide pipes 13 with the water collection groove 12 when the rolling cushion layer 5 is laid to the top surface, installing drainage ditches 2 at the left side and the right side of the rolling cushion layer 5 after rolling and laying of the rolling cushion layer 5 are completed, arranging seepage wells 3 in the drainage ditches 2 at intervals, laying an anti-seepage film 6, putting permeable aggregates 11 into the seepage wells 3 firstly after the anti-seepage film 6 is laid, filling the seepage wells 3 with the permeable aggregates 11 completely, and then piling the permeable aggregates 11 in the drainage ditches 2 and the water collection.

And after the processes are finished, laying the buried pipe 1, and after the buried pipe 1 is laid, rolling and backfilling the pipe ditch by using original soil. After the backfilling is finished, the laying structure suitable for parallel 2 or 3 or a plurality of large-diameter buried pipes is manufactured.

It should be noted that the above-mentioned embodiments are only some embodiments of the present invention, and not all embodiments. The above embodiments are merely preferred embodiments of the present invention, but the scope of the present invention is not limited to the above embodiments, and all technical solutions belonging to the idea of the present invention belong to the scope of the present invention. It should be noted that, for those skilled in the art, based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without any inventive work are within the scope of the present invention.

Claims (8)

1. The utility model provides a large pipe diameter pipe laying of collapsible loess area structure, its characterized in that: the buried pipe type water seepage drainage structure comprises a buried pipe (1), a drainage ditch (2), a water seepage well (3), a longitudinal curtain (41), a transverse curtain (42), a rolling cushion layer (5), a sleeve valve pipe (7), a slurry injection layer (9) and a covering layer (10), wherein an arc-shaped groove is formed in the rolling cushion layer (5), two sides of the arc-shaped groove are provided with downward slopes, an anti-seepage film (6) is paved on the slopes, the drainage ditch (2) is arranged at the lower end of the slopes, the water seepage well (3) is arranged in the drainage ditch (2) at intervals, the longitudinal curtain (41) and the transverse curtain (42) are located in a pipe foundation dug by the buried pipe (1), the longitudinal curtain (41) comprises a left longitudinal curtain (410) and a right longitudinal curtain (411), the left longitudinal curtain (410) and the right longitudinal curtain (411) are continuously distributed along the axial direction of the buried pipe (1), and the left longitudinal curtain (410) and the right longitudinal curtain (411) are symmetrically arranged along the axis of the buried pipe (1), Sleeve valve pipes (7) and transverse curtains (42) are arranged at intervals between the right longitudinal curtains (411); the bottom of the left longitudinal curtain (410) and the bottom of the right longitudinal curtain (411) are connected through a grouting material layer (9), the lower end of a sleeve valve pipe (7) extends into the grouting material layer (9), a plurality of grouting holes (8) are formed in the lower end of the sleeve valve pipe (7), a paving layer (10) is arranged on original loess between the left longitudinal curtain (410) and the right longitudinal curtain (411), and a rolling cushion layer (5) is arranged on the paving layer (10).

2. The large-pipe-diameter pipe laying structure in the collapsible loess region according to claim 1, wherein: the material of the rolling cushion layer (5) is lime soil and/or clay.

3. The large-pipe-diameter pipe laying structure in the collapsible loess region according to claim 1, wherein: the material of the paving layer (10) is lime soil and/or clay.

4. The large-pipe-diameter pipe laying structure in the collapsible loess region according to claim 1, wherein: the material of the impermeable membrane (6) is polyvinyl chloride and/or polyethylene and/or EVA.

5. The large-pipe-diameter pipe laying structure in the collapsible loess region according to claim 1, wherein: permeable aggregates (11) are thrown in the drainage ditch (2) and the permeable well (3).

6. The large-pipe-diameter pipe laying structure in the collapsible loess region according to claim 5, wherein: the pervious aggregate (11) is made of recycled concrete aggregate and/or common broken stone aggregate and/or coarse sand material.

7. The large-diameter buried pipe laying structure in the collapsible loess region according to claim 1, further comprising a water collection tank (12) and a water guide pipe (13), wherein the water collection tank (12) is arranged on the rolling cushion layer (5) and between two adjacent buried pipes (1), the water guide pipe (13) is arranged in the rolling cushion layer (5), two ends of the water guide pipe (13) are respectively communicated with the drainage ditch (2) and the water collection tank (12), and the drainage ditch (2) and the water collection tank (12) are in a precast concrete form and/or a precast resin material form.

8. The construction method for the large-pipe-diameter pipe laying structure in the collapsible loess area is characterized by comprising the following steps of:

1) measuring and paying off operation, excavating the pipe trench base to the height of an excavated surface, and leveling the trench base;

2) sequentially manufacturing a longitudinal curtain (41) and a transverse curtain (42) along the design position of the trench bottom of the trench, after the manufacture of all the curtains is finished, inserting a sleeve valve tube (7) on the basis of the trench bottom between the longitudinal curtains (41), and pressure-filling grouting material (9) into the basement part through a plurality of grouting holes (8) formed in the lower end of the sleeve valve tube (7), so that the bottoms of the longitudinal curtain (41) and the transverse curtain (42) are serially communicated by the grouting material (9);

3) excavating partial trench bottom foundation soil layers at the tops of the longitudinal curtains (41) and the transverse curtains (42) below the elevation of the excavation surface;

4) constructing a drainage ditch (2) and a water seepage well (3) at the outer side of the longitudinal curtain (41) according to design requirements;

5) constructing a paving layer (10) on the top of the longitudinal curtain (41) and the transverse curtain (42);

6) the permeable aggregate (11) is thrown and filled in the permeable well (3) and the drainage ditch (2);

7) layering rolling and filling the rolling cushion layer (5) until the construction of the rolling cushion layer (5) is finished;

8) flattening the rolled cushion layer (5) after construction, and paving an impermeable film (6) on the rolled cushion layer;

9) hoisting and installing the buried pipe (1), and connecting adjacent pipe sections;

10) and backfilling the original soil, carrying out layered rolling, and completing construction after backfilling to the original ground elevation.

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