CN112323560B - Roadbed construction settlement control system in complex soft foundation environment - Google Patents

Abstract

The invention provides a roadbed construction settlement control system and a roadbed construction method in a complex soft foundation environment. The system comprises CFG piles, pipe wells and drainage plates which are distributed at intervals, wherein the CFG piles are mutually provided with rigid core piles which are connected with reinforced concrete in an intersecting and/or attaching mode, and the intersecting parts or the attaching parts of the rigid core piles and the CFG piles are made of concrete. In the process that the discrete pile is extruded to the periphery by the rotary drilling rig, the soil between the second pile position and the first pile position is split, and a rigid connection structure connected between the CFG pile and the rigid core pile is formed between the first pile position and the second pile position along with cement mortar filled into cracks in the guniting operation; simultaneously, the process of splitting second pile position periphery weak soil also can extrude the moisture in the soft soil to tube-well and plastics drain bar direction for concrete pile cover surface is the fracturing surface, combines more closely with the soft soil, thereby has improved holistic structural stability.

Description

Roadbed construction settlement control system in complex soft foundation environment

Technical Field

The invention relates to the technical field of settlement control of bridgehead and high-fill roadbed under complex soft foundation environment, in particular to a settlement control system and a settlement control method for roadbed construction under complex soft foundation environment.

Background

The middle-opened highway project is built in a BOT + EPC investment management mode, and has the characteristics of large engineering scale, complex technical conditions, large construction difficulty, wide operation surface distribution, large land acquisition and removal difficulty, multiple environment sensitive points, multiple participating units, multiple work cross factors and the like, the processing length of the whole special roadbed is 26.329km, the whole special roadbed is mainly distributed in a new meeting area of a river section, the project soft foundation has large processing capacity and is mostly a deep silt soft foundation, the water content is high, and the processing depth reaches 20-30 m; according to the driving experience of municipal roads, expressways and the like established in the current river area, the condition of bumping at the bridge head is serious, the settlement of the roadbed after construction is large, the later maintenance cost is high, and the driving safety risk is high.

The CFG pile is a cement fly ash gravel pile, which is a variable-strength pile with certain strength and is prepared by mixing gravel, stone chips, sand and fly ash with cement and adding water and mixing through various pile-forming machines. The CFG pile is a low-strength concrete pile, can fully utilize the combined action of bearing capacity of soil among the piles, can transmit load to a deep foundation, has better technical performance and economic effect, has wider application range, and can be suitable for treating cohesive soil, silt soil and sandy soil, and foundations such as mucky soil with a pile end having a relatively hard soil layer and a bearing capacity standard value not less than 70KPa, non-under-consolidated artificial filling soil and the like, wherein an important part in a construction site is a tower crane, and the tower crane needs to be arranged on the CFG pile in the construction process. Common tower crane CFG stake generally faces in the existing market, and it has only set up a king pile, so it is in soft foundation use, and external thrust can't be fully dispelled, in case the CFG stake receives frequent rocking, thereby the stake body earth all around just can be promoted and extrude together, great gap just can appear all around in the later stake body for the stability of stake body reduces, leads to equipment security to reduce.

The prior patent CN201910532560.4 discloses a CFG pile for a tower crane soft foundation and a construction method, comprising a foundation, wherein a pile body groove is arranged in the foundation, a main pile body is embedded in the pile body groove, a plurality of auxiliary pile grooves are arranged on the outer side of the pile body groove at equal intervals, a reinforcing auxiliary pile sleeve for reinforcing the ground gripping force of the main pile body is arranged in each auxiliary pile groove, an auxiliary mounting frame is slidably connected in each reinforcing auxiliary pile sleeve, the equipment is provided with the reinforcing auxiliary pile sleeves around the main pile body, when the pile body is punched, a plurality of auxiliary pile grooves can be drilled around the pile body groove, the reinforcing auxiliary pile sleeves are arranged in the auxiliary pile grooves, so that the auxiliary pile grooves are communicated with the pile body groove, when a user injects materials, the auxiliary pile grooves and the pile body groove can be filled simultaneously, after the materials are dried, the auxiliary pile bodies around the main pile body can fully improve the ground gripping force of the pile body, so that the main pile body is strongly shaken, soil around the pile body can not be pushed and extruded easily, and the stability of the pile body is improved, so that the safety of the tower crane in use is higher.

However, if the existing CFG pile is constructed in soft soil, because the underground water level of a soft soil foundation is high, the water content of a soil body is high, and larger super-gap water pressure is easily generated in pile foundation construction and is difficult to dissipate. This problem can lead to soil body level, vertical displacement, can cause pile body come-up, pile position skew even, influences basic quality and stability. Above-mentioned form of ally oneself with stake more still can't be close whole pile that ally oneself with and shift easily or the problem that heels to lead to the roadbed under the soft basic environment to have stability not enough, the uncontrollable problem of settlement volume at will.

Disclosure of Invention

The invention aims to provide a roadbed construction settlement control system under a complex soft foundation environment with stable pile bodies, which adopts the following technical scheme:

a roadbed construction settlement control system in a complex soft foundation environment comprises CFG piles, pipe wells and drainage plates which are distributed at intervals, wherein the CFG piles are mutually intersected and/or attached with rigid core piles made of reinforced concrete materials, and the intersection parts or the attachment parts of the rigid core piles and the CFG piles are made of concrete materials.

Furthermore, an anti-seepage pile sleeve is further coated on the periphery of the CFG pile, the anti-seepage pile sleeve is formed by casting concrete and an anti-seepage ball doped in the concrete in situ, the anti-seepage ball comprises an outer shell made of PPS (polyphenylene sulfide), plugging and water stopping powder, an inner shell made of PPS and a hydrogel block which are sequentially arranged from outside to inside, and the thickness of the outer shell is larger than that of the inner shell.

Further, the volume of the inner shell is no more than one third of the volume of the outer shell.

Further, the periphery of the rigid core pile is wrapped with mutually matched and complementary concrete pile sleeves, and the rigid core pile is eccentrically arranged in the concrete pile sleeves and is deviated to one side close to the rigid core pile.

Furthermore, a positioning pile sleeve is further wrapped on the periphery of the CFG pile, the positioning pile sleeve is formed by casting a pile sleeve main body made of sulfur mortar and anti-seepage balls doped in the pile sleeve main body in a cast-in-place mode, the anti-seepage balls are connected through heat conducting wires, each anti-seepage ball comprises an outer shell made of aluminum, leaking stoppage water stopping powder, an inner shell made of PPS (polyphenylene sulfide) and a hydrogel block, and the thickness of the outer shell is larger than that of the inner shell.

Further, at least three rigid core piles are uniformly distributed around the periphery of the CFG pile.

Furthermore, a rigid core pile is arranged between two adjacent CFG piles, and the axis of the rigid core pile is located on one side of the central connecting line of the two CFG piles.

The invention also aims to provide a roadbed construction settlement control method in a complex soft foundation environment, which adopts the following technical scheme:

a subgrade construction settlement control method in a complex soft foundation environment comprises the following steps:

s100, arranging a plurality of pipe wells and plastic drainage plates in a soft soil layer to be constructed to perform pumping and drainage operation;

s200, performing construction operation of the CFG pile on the first pile position, and forming the CFG pile in a soft soil layer;

s300, performing construction operation of discrete piles on a second pile position intersecting and/or attached to the first pile position, and driving discrete materials into soft soil;

s400, constructing a concrete pile sleeve by using a rotary drilling rig in a mode of rotating forward and spraying grout simultaneously in the discrete pile, and continuously performing drainage operation on the pipe well and the plastic drainage plate;

s500, casting and forming the rigid core pile in the concrete pile sleeve in a cast-in-place mode.

The invention has the beneficial effects that:

in the process that the discrete pile is extruded to the periphery by the rotary drilling rig, the soil between the second pile position and the first pile position is split, and a rigid connection structure connected between the CFG pile and the rigid core pile is formed between the first pile position and the second pile position along with cement mortar filled into cracks in the guniting operation; simultaneously, the process of splitting second pile position periphery weak soil also can extrude the moisture in the soft soil to tube-well and plastics drain bar direction for concrete pile cover surface is the fracturing surface, combines more closely with the soft soil, thereby has improved holistic structural stability.

The above and other objects, advantages and features of the present invention will become more apparent to those skilled in the art from the following detailed description of specific embodiments thereof, taken in conjunction with the accompanying drawings.

Drawings

Some specific embodiments of the invention will be described in detail hereinafter, by way of illustration and not limitation, with reference to the accompanying drawings. The same reference numbers in the drawings identify the same or similar elements or components. Those skilled in the art will appreciate that the drawings are not necessarily drawn to scale. In the drawings:

fig. 1 is a schematic structural view of a subgrade construction settlement control system in a complex soft foundation environment according to a first embodiment of the invention;

FIG. 2 is a schematic block diagram of the impervious ball of FIG. 1;

fig. 3 is a schematic structural view of a subgrade construction settlement control system in a complex soft foundation environment according to a second embodiment of the invention.

The reference numbers used in the drawings are as follows:

10 CFG pile (pile foundation) is adopted,

20 of the anti-seepage pile sleeve, wherein,

21 the outer shell of the device is provided with a shell,

22 stopping the leakage of the water and stopping the water powder,

23 the inner shell is made of a material,

24 the mass of the hydrogel, and the gel,

30 of the rigid core piles, and a rigid core pile,

40 discrete piles.

Detailed Description

The first embodiment:

the subgrade construction settlement control system in the complex soft foundation environment of the embodiment is a structure for obtaining an available subgrade through construction of a soft soil layer, and because the system is formed after construction, the following method firstly introduces the subgrade construction settlement control method in the complex soft foundation environment, and then introduces the subgrade construction settlement control system in the complex soft foundation environment to explain and explain the technical scheme related to the embodiment.

The roadbed construction settlement control method under the complex soft foundation environment comprises the following steps:

and S100, arranging a plurality of pipe wells and plastic drainage plates in the soft soil layer to be constructed for pumping and draining water.

In a soft soil layer at the periphery of a pile position of a stiff composite pile to be constructed, a plurality of pipe wells and plastic drainage plates are arranged for pumping and draining water, so that the underground water level is reduced, the water content of a soil body is reduced, the density is improved, and the upper soft soil is hardened and compacted. The shooting mode of the pipe well and the plastic drainage plate can refer to the prior patent CN111535293A, namely, the pipe well and the plastic drainage plate are arranged in a soft soil foundation; the top of the foundation is provided with a stacking load; arranging a water drawing area in the periphery of the soft soil foundation, respectively laying a drainage sand cushion layer on the surface of the soft soil foundation and the surface of the water drawing area, and arranging drainage pipes in the sand cushion layer, wherein the embedding depth is not less than 20 cm; the sealing film is arranged on the sand cushion layer; arranging a water suction pipeline in the pipe well, wherein the water suction pipeline is connected with a vacuum pump; arranging a water drawing tank after the water drawing area is excavated; the water drawing tank is provided with a water inlet and a water outlet, the water inlet is connected with the vacuum pump, and the water outlet is connected with the centrifugal pump at the bottom of the water drawing tank.

And S200, performing construction operation of the CFG pile 10 on the first pile position, and forming the CFG pile 10 in a soft soil layer.

The CFG pile 10 is a cement fly ash gravel pile located in the core, and is a variable-strength pile with a certain strength, which is made of gravel, stone chips, sand, fly ash mixed with cement and mixed with water, and is formed by various pile forming machines. The seepage-proofing pile sleeve 20 coated on the periphery of the CFG pile 10 is not included, but the construction process of the seepage-proofing pile sleeve 20 is before the CFG pile 10, so the construction process of the step is as follows:

and S210, drilling in the soft soil layer by using a long spiral drilling machine until the drilling depth reaches a set depth.

And S220, lifting the drill bit of the long spiral drilling machine to a designated height.

S230, pumping concrete mixed with anti-seepage balls into a central channel of the long spiral drilling machine by using a pump to perform anti-seepage pile construction, wherein the anti-seepage balls are doped into the concrete in a proportion that each cubic concrete is doped with not less than 13 anti-seepage balls, and the volume of the anti-seepage balls in each cubic concrete accounts for 30-60 percent, so that the outer shell 21 of part or all of the anti-seepage balls can be crushed by a drill rod of the long spiral drilling machine in the secondary drilling process of the long spiral drilling machine, and simultaneously, under the drilling centrifugal action of the long spiral drilling machine, the anti-seepage balls are crushed at the critical position of pile edge soil to play a good water fixing role; meanwhile, wherein:

the concrete can be one or more than two of lightweight concrete, material used by the CFG pile 10 and common concrete;

the seepage-proofing ball comprises an outer shell 21 made of PPS, plugging water-stopping powder 22, an inner shell 23 made of PPS and a hydrogel block 24, wherein the outer shell 21, the plugging water-stopping powder 22, the inner shell 23 and the hydrogel block 24 are sequentially arranged from outside to inside, the thickness of the outer shell 21 is larger than that of the inner shell 23, and the volume of the inner shell 23 is not larger than one third of the volume of the outer shell 21.

And S240, after the drill is lifted to the specified height of the ground, introducing compressed air into the long spiral drilling machine, and emptying residues in the center hole of the long spiral drilling machine.

And S250, performing secondary drilling construction on the seepage-proofing pile by using the long spiral drilling machine until the seepage-proofing pile is drilled through, continuously drilling for 10-35m, and stopping drilling.

And S260, after the pile is upwards drilled for 3-8m, the pouring construction of the CFG pile 10 is started.

And S270, after the secondary lifting drilling is carried out to the designated height, the construction of the CFG pile 10 is completed.

Preferably, in the above embodiment, the material of the anti-seepage pile may also be replaced by sulfur mortar doped with anti-seepage balls, which is different from the above construction process in that:

s230, pumping concrete mixed with anti-seepage balls into a central channel of the long spiral drilling machine by using a pump to perform positioning pile construction, wherein the anti-seepage balls are doped in the concrete in a proportion that each cubic concrete is doped with not less than 13 anti-seepage balls, the anti-seepage balls are connected through heat conduction wires, a plurality of heat conduction wires are arranged between every two connected anti-seepage balls and are connected to each position of the anti-seepage ball in a spot welding manner, and the volume percentage of the anti-seepage balls in each cubic concrete is 30-60%, wherein:

the concrete can be one or more than two of lightweight concrete, material used by the CFG pile 10 and common concrete;

the anti-seepage ball comprises an outer shell 21 made of aluminum, plugging water stopping powder 22, an inner shell 23 made of PPS (polyphenylene sulfide) and a hydrogel block 24 which are sequentially arranged from outside to inside, wherein the thickness of the outer shell 21 is larger than that of the inner shell 23.

S250, electrifying the positioning pile to remove the solid state of the sulfur mortar; and meanwhile, performing secondary drilling construction on the seepage-proofing pile by using the long spiral drilling machine until the seepage-proofing pile is drilled through, continuously drilling for 10-35m, and stopping drilling.

And S300, performing construction operation of the discrete body pile on a second pile position intersected with the first pile position, and driving the discrete body material into soft soil.

Wherein the part of the second pile location intersecting the first pile location is less than one fifth of either the second pile location or the first pile location, but the intersection must comprise a part of the CFG pile 10, i.e. what is required in this step is the intersection of the CFG pile 10 and the discrete pile, while in the case of the cut-off pile also intersecting the discrete pile, the intersection of the CFG pile 10 and the discrete pile will be enclosed in the space enclosed by the rigid core pile 30, the CFG pile 10 and the cut-off pile. The discrete material of the discrete pile comprises at least one hard material of broken stone, pebble, sand, steel slag and slag.

S400, constructing a concrete pile sleeve by using a rotary drilling rig in a mode of simultaneously screwing in and spraying slurry in a scattered body pile, and simultaneously continuing drainage operation of the pipe well and the plastic drainage plate.

Specifically, a cement soil pile is constructed in the granular material pile, a rotary drilling rig is used for carrying out stirring and high-pressure air injection, powder spraying or slurry spraying operation eccentrically in the granular material pile and close to one side of the CFG pile 10, surrounding pipe wells continue to carry out pumping and drainage operation simultaneously, the sprayed air, powder or slurry penetrates through the granular material and splits the peripheral soft soil of the pile position and moves towards the pipe well, so that the powder or slurry is easily absorbed by the soil body, the intersected side is embedded into the concrete block body again, and the original soft soil of the other sides is solidified into a harder soil body containing cement. Wherein the powder or slurry is the powder of cement, fly ash, silica powder, steel slag or slag, and the slurry is prepared by water distribution.

S500, the rigid core pile 30 is cast in situ in the concrete pile sleeve.

Wherein the axes of the discrete pile, the rigid core pile 30 and the CFG pile 10 are aligned. The rigid core pile 30 includes a cast-in-place concrete pile or a cast-in-place reinforced concrete pile.

However, when the sulfur mortar is selected as the main material of the positioning piles at the periphery of the CFG pile 10, the number of the rigid core piles 30 to be formed should not be less than three, and the three rigid core piles 30 need to be uniformly distributed around the CFG pile 10.

Because the seepage-proofing piles and the positioning piles are made of different materials except for the outer shell 21, and the rest of the structure is the same, the seepage-proofing piles are taken as an example to explain the roadbed construction settlement control system in the complex soft foundation environment formed by the construction method. Referring to fig. 1 and 2, the subgrade construction settlement control system in the complex soft foundation environment comprises:

the pile comprises CFG piles 10, pipe wells, drainage plates, rigid core piles 30, seepage-proofing pile sleeves 20 and scattered pile sleeves 40 which are distributed at intervals.

The CFG piles 10 are mutually intersected and connected with the rigid core piles 30 made of reinforced concrete, and the intersection parts of the rigid core piles 30 and the CFG piles 10 are made of concrete. The CFG pile 10 is further coated with an anti-seepage pile sleeve 20 on the periphery, the anti-seepage pile sleeve 20 is formed by casting concrete and anti-seepage balls doped in the concrete in situ, each anti-seepage ball comprises an outer shell 21 made of PPS (polyphenylene sulfide), plugging and water stopping powder 22, an inner shell 23 made of PPS and a hydrogel block 24, the outer shell 21 is thicker than the inner shell 23, and the inner shell 23 is not larger than one third of the volume of the outer shell 21. The periphery of the rigid core pile 30 is wrapped with mutually matched and complementary discrete pile sleeves 40, and the rigid core pile 30 is eccentrically arranged in the discrete pile sleeves 40 and is eccentrically arranged at one side close to the rigid core pile 30. At least three rigid core piles 30 are uniformly distributed around the periphery of the CFG pile 10.

Second embodiment:

the difference between this embodiment and the first embodiment is that, referring to fig. 3, a rigid core pile 30 is disposed between two adjacent CFG piles 10, and the axis of the rigid core pile 30 is located on one side of the center-to-center line of the two CFG piles. From the practical point of view of construction, the rigid core piles 30 are located on the side close to the roadside, so that the rigid core piles 30 can be used to play a good role of a "fence" for the CFG piles 10. Meanwhile, the preferable surrounding coating material of the CFG pile is non-sulfur mortar, because the rigidity of the positioning pile sleeve is influenced after the electrification is removed, and the CFG pile 10 is supported by a single side, the seepage-proofing pile sleeve 20 with certain strength is selected, and the better choice is realized.

Thus, it should be appreciated by those skilled in the art that while a number of exemplary embodiments of the invention have been illustrated and described in detail herein, many other variations or modifications consistent with the principles of the invention may be directly determined or derived from the disclosure of the present invention without departing from the spirit and scope of the invention. Accordingly, the scope of the invention should be understood and interpreted to cover all such other variations or modifications.

Claims (6)

1. The subgrade construction settlement control system under the complex soft foundation environment comprises CFG piles, pipe wells and drainage plates which are distributed at intervals, and is characterized in that the CFG piles are mutually provided with rigid core piles which are connected with reinforced concrete in an intersecting and/or attaching mode, and the intersecting parts or the attaching parts of the rigid core piles and the CFG piles are made of concrete;

the CFG pile is characterized in that an anti-seepage pile sleeve is further coated on the periphery of the CFG pile, the anti-seepage pile sleeve is formed by casting concrete and anti-seepage balls doped in the concrete in situ, each anti-seepage ball comprises an outer shell made of PPS (polyphenylene sulfide), plugging water stopping powder, an inner shell made of PPS and a hydrogel block which are sequentially arranged from outside to inside, and the thickness of the outer shell is larger than that of the inner shell.

2. The subgrade construction settlement control system in the complex soft foundation environment of claim 1, wherein the volume of the inner shell is not more than one third of the volume of the outer shell.

3. The system for controlling subgrade construction settlement in the environment of complex soft foundation according to claim 1, wherein the rigid core pile is wrapped with mutually matched and complementary concrete pile sleeves, and the rigid core pile is eccentrically arranged in the concrete pile sleeves and is biased to one side close to the CFG pile.

4. The system for controlling subgrade construction settlement in the environment of complex soft foundation according to claim 1, which is characterized in that a positioning pile sleeve is further coated on the periphery of the CFG pile, the positioning pile sleeve is formed by casting a pile sleeve main body made of sulfur mortar and anti-seepage balls doped in the pile sleeve main body in situ, the anti-seepage balls are connected through heat conducting wires, each anti-seepage ball comprises an outer shell made of aluminum, plugging and water stopping powder, an inner shell made of PPS (polyphenylene sulfide) and a hydrogel block, the outer shell is thicker than the inner shell.

5. The subgrade construction settlement control system in the complex soft foundation environment according to any one of claims 1-4, characterized in that at least three rigid core piles are uniformly distributed around the CFG piles in the circumferential direction.

6. The subgrade construction settlement control system in the complex soft foundation environment according to any one of claims 1-4, characterized in that a rigid core pile is arranged between two adjacent CFG piles, and the axis of the rigid core pile is positioned at one side of the central connecting line of the two CFG piles.

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