阅读说明：本技术 一种变截面废旧轮胎桩复合地基及其施工工艺 (Variable-section waste tire pile composite foundation and construction process thereof ) 是由 岳红亚 徐润 张常勇 李怀峰 毕玉峰 刘晓威 于 2021-09-10 设计创作，主要内容包括：本发明属于道路岩土工程领域,涉及一种变截面废旧轮胎桩复合地基及其施工工艺,主要包括废旧轮胎条带、压烫土工布和冶炼废渣或建筑垃圾或尾矿等固废填料。本发明可充分发挥地基抗剪强度和承载性能,提高散体桩的承载力和复合地基抗滑性能优化施工设计,提高大宗固废材料的消耗率,简化施工工艺,降低工程成本,缩短工程建设周期,解决大宗固废材料带来的环境污染和土地占用问题,具有显著的环境意义和社会意义。(The invention belongs to the field of road geotechnical engineering, and relates to a variable cross-section waste tire pile composite foundation and a construction process thereof. The invention can give full play to the shear strength and the bearing performance of the foundation, improve the bearing capacity of the discrete pile and the skid resistance of the composite foundation, optimize the construction design, improve the consumption rate of a large amount of solid waste materials, simplify the construction process, reduce the engineering cost, shorten the engineering construction period, solve the problems of environmental pollution and land occupation caused by the large amount of solid waste materials, and has obvious environmental significance and social significance.)

1. The utility model provides a variable cross section junked tire stake composite foundation which characterized in that, the pile body that composite foundation adopted is interweaved by junked tire strip and forms, the pile body includes: a plurality of conventional cross-sectional sections and a plurality of variable cross-sectional sections; the inner wall of the waste tire strip is provided with a pressing geotextile to form a composite geotechnical packaging body, and solid waste fillers are filled in the pile body.

2. The variable cross-section waste tire pile composite foundation of claim 1, wherein the interweaving comprises: the radial tire strip and the axial tire strip are vertically crossed, the axial tire strip is arranged on the inner side, the radial tire strip is arranged on the outer side, and a bonding agent and a fastening device are arranged at the crossed position of the radial tire strip and the axial tire strip; preferably, a modified epoxy glue is used as the adhesive, or a pre-tightening bolt and a square rigid backing plate are used for fastening.

3. The variable cross-section waste tire pile composite foundation as claimed in claim 2, wherein the distribution depth of the variable cross-section is the same as that of the conventional cross-section, the diameter of the maximum cross-section is 1.5-2.5 times of that of the conventional cross-section, the middle part of the variable cross-section is in equidistant transition, and preferably, the diameter of the maximum cross-section is 2 times of that of the conventional cross-section.

4. The variable cross-section waste tire pile composite foundation of claim 2, wherein the radial tire strip with the conventional cross-section segment is an integral annular structure formed by directly cutting off a tire wall of a waste tire.

5. The variable cross-section waste tire pile composite foundation as claimed in claim 2, wherein the manufacturing method of the variable cross-section radial tire strip is as follows: the used tire is directly cut off from the tire wall to form an integral annular structure, the integral annular structure is transversely cut to form strips, and the strips are connected through the end parts to form large-diameter annular structures with different circumferences.

6. The variable cross-section waste tire pile composite foundation as claimed in claim 2, wherein the vertical distance between the radial tire strips of the variable cross-section should not be more than 10 cm;

alternatively, at the maximum diameter of the section of variable cross-section, a widened tire strip should be used.

7. The variable cross-section waste tire pile composite foundation of claim 1, wherein the solid waste material comprises: smelting waste slag, construction waste and tailings.

8. The variable cross-section waste tire pile composite foundation as claimed in claim 1, wherein the waste tire strip is formed by directly cutting off the sidewalls of the waste tire or cutting the crown along the tread grooves.

9. A construction method of a variable cross-section waste tire pile composite foundation is characterized by comprising the following steps:

testing the performance of the variable cross-section waste tire pile;

determining the bearing capacity of the reinforced pile-soil composite foundation, and determining various design parameters of the variable cross-section waste tire pile according to the bearing capacity;

manufacturing a composite geotechnical packaging body meeting the requirements according to the determined design parameters;

drilling;

sleeve installation: installing a composite geotechnical packaging body in the sleeve, and putting the composite geotechnical packaging body and the sleeve into the drilled hole together;

filling and filling: filling solid waste materials into the composite geotechnical packaging body, stopping filling when the filling height reaches the bottom surface of the section 1 section of variable cross section, and lifting the sleeve upwards to the top surface of the solid waste materials;

and (3) vibrating and compacting the conventional section: after the filling of the layer 1 solid waste material is finished, vibrating and compacting;

vibrating and compacting the variable section: after the compaction of the section 1 conventional section is finished, continuously filling solid waste filler to the top of the section 1 variable section, and then lifting the sleeve upwards to the top surface of the filler for vibration compaction;

repeating the steps of filling the filler, compacting by vibration of the conventional section and compacting by vibration of the variable section until the filler is filled to the design elevation of the pile foundation;

laying a cushion layer: after the construction of the pile foundation is finished, a top cushion layer is laid, a layer of grid reinforcement material formed by manufacturing waste tire walls and connecting tire strips is arranged on the cushion layer and the top of the pile foundation, and the grid reinforcement material is connected with the longitudinal tire strips of the reinforcement cage.

10. Use of a variable cross-section waste tyre pile composite foundation according to any one of claims 1 to 8 in road geotechnics.

Technical Field

The invention belongs to the field of road geotechnical engineering, and particularly relates to a variable-section waste tire pile composite foundation and a construction process thereof, in particular to a waste tire strip and geotextile combined solid waste material pile composite foundation for reinforcing a soft foundation and an on-site construction process thereof.

Background

The information in this background section is only for enhancement of understanding of the general background of the invention and is not necessarily to be construed as an admission or any form of suggestion that this information forms the prior art that is already known to a person of ordinary skill in the art.

With the continuous expansion of the construction scale of roads and railway projects in China, the reinforcement and treatment of soft foundations become the problem of the normalized projects facing the road construction. At present, the common soft foundation reinforcement treatment method mainly comprises dynamic compaction, shallow layer replacement, pile-soil composite foundation, preloading and the like. In the various reinforcement methods, the pile-soil composite foundation is widely applied to soft foundation reinforcement due to the advantages of wide application range, obvious reinforcement effect and the like. For soft foundations in special areas, such as areas with high underground water level or soil layers with poor drainage conditions, flexible gravel piles, sand piles and muck piles are often adopted for reinforcement treatment. Because the pile body is internally provided with the natural drainage channel, the drainage process can be accelerated, the consolidation time of the foundation is reduced, and the pile body has obvious reinforcement effect in the foundation. However, because of the lack of radial restraint, large radial deformation is likely to occur when the pile is subjected to an upper load, and the bearing capacity of the pile foundation is reduced, so that the exertion of the bearing capacity of the gravel pile depends on the restraining effect of the soil around the pile to a great extent. In order to solve the problem, a novel geotechnical packaging gravel/waste residue pile is provided at home and abroad, and by wrapping geotechnical cloth and geogrid externally, the technical advantage of high tensile strength of the geogrid is fully exerted to provide radial restraint, and meanwhile, silt can be prevented from permeating, the inner drainage channel is kept smooth, and the bearing capacity of the composite foundation is improved to a certain extent. However, since this type of pile foundation belongs to a suspension pile, the bearing capacity is mainly provided by the friction resistance around the pile, and the shear strength of the soft foundation soil itself is low, therefore, in some high fill and other road sections with high requirements for the bearing capacity of the foundation, the bearing capacity of the composite foundation can only be improved by increasing the pile diameter, the pile length, the pile number and other methods, which results in an increase in the engineering construction cost and an extension of the engineering construction period. Meanwhile, the pile foundation of the type still belongs to a flexible pile, the self shear resistance is poor, and the roadbed slippage damage caused by insufficient shear resistance of the substrate easily occurs at the position of the slope toe. Due to the technical problems, the pile foundation of the type is difficult to popularize and apply in large areas in engineering.

On the other hand, with the continuous development of economy, the production amount and the stockpiling amount of materials such as waste residues, construction wastes, waste tires, tailings and the like of industrial solid wastes are also increased year by year. There are studies showing that: the total stock of industrial solid waste in some countries exceeds 600 million tons, and 30 million tons are newly added each year. The generation and the stacking of the industrial solid wastes not only pollute the environment and occupy a large amount of land resources, but also easily induce secondary accidents such as fire, collapse of stacked bodies and the like, and seriously threaten the safety of human life and property. Although the utilization rate of industrial solid wastes has increased by more than 50% year by year, the industrial solid wastes still have larger lifting space. Therefore, expanding a large amount of industrial solid waste comprehensive utilization channels, innovating a solid waste recycling and utilizing technology, reducing the industrial solid waste recycling cost and resource consumption, and helping to realize 'carbon peak reaching' and 'carbon neutralization' become a technical problem to be solved urgently in the current industrial industry. Road engineering has become the main battlefield for recycling a large amount of industrial solid wastes gradually due to the characteristic of large mineral resource consumption. Therefore, how to innovate the solid waste utilization technology and equipment, increase the utilization rate of the industrial solid waste in road engineering, and further increase the consumption of the industrial solid waste becomes a problem to be considered by engineering constructors.

Disclosure of Invention

The invention provides a variable cross-section waste tire pile composite foundation and a field construction process thereof, aiming at solving the technical problems and further improving the recycling efficiency of a large amount of industrial solid wastes. Compared with the prior art, the invention can realize that: the bearing capacity of the existing discrete pile composite foundation is improved, the shear strength of the contact surface of the foundation and the roadbed is enhanced, the number of discrete piles in the engineering is reduced, the pile length is shortened, the pile diameter is reduced, the engineering design of the discrete pile composite foundation is optimized, and the method has obvious engineering technical advantages; the method increases the consumption of a large amount of industrial solid wastes such as waste tires, construction wastes, industrial waste residues, tailings and the like, reduces the secondary processing cost in the process of recycling the solid wastes, has obvious economic and social benefits, and has wide engineering popularization and application prospects.

In order to achieve the technical purpose, the invention adopts the following technical scheme:

in a first aspect of the invention, a variable cross-section waste tire pile composite foundation is provided, in which a pile body adopted by the composite foundation is formed by interweaving waste tire strips, and the pile body comprises: a plurality of conventional cross-sectional sections and a plurality of variable cross-sectional sections; the inner wall of the waste tire strip is provided with a pressing geotextile to form a composite geotechnical packaging body, and solid waste fillers are filled in the pile body.

In a second aspect of the invention, a construction method of a variable cross-section waste tire pile composite foundation is provided, which comprises the following steps:

testing the performance of the variable cross-section waste tire pile;

determining the bearing capacity of the reinforced pile-soil composite foundation, and determining various design parameters of the variable cross-section waste tire pile according to the bearing capacity;

manufacturing a composite geotechnical packaging body meeting the requirements according to the determined design parameters;

drilling;

sleeve installation: installing a composite geotechnical packaging body in the sleeve, and putting the composite geotechnical packaging body and the sleeve into the drilled hole together;

filling and filling: filling solid waste materials into the composite geotechnical packaging body, stopping filling when the filling height reaches the bottom surface of the section 1 section of variable cross section, and lifting the sleeve upwards to the top surface of the solid waste materials;

and (3) vibrating and compacting the conventional section: after the filling of the layer 1 solid waste material is finished, vibrating and compacting;

vibrating and compacting the variable section: after the compaction of the section 1 conventional section is finished, continuously filling solid waste filler to the top of the section 1 variable section, and then lifting the sleeve upwards to the top surface of the filler for vibration compaction;

repeating the steps of filling the filler, compacting by vibration of the conventional section and compacting by vibration of the variable section until the filler is filled to the design elevation of the pile foundation;

laying a cushion layer: after the construction of the pile foundation is finished, a top cushion layer is laid, a layer of grid reinforcement material formed by manufacturing waste tire walls and connecting tire strips is arranged on the cushion layer and the top of the pile foundation, and the grid reinforcement material is connected with the longitudinal tire strips of the reinforcement cage.

In a third aspect of the invention, the application of any one of the variable cross-section waste tire pile composite foundations in road geotechnical engineering is provided.

The invention has the beneficial effects that:

(1) the existing gravel pile has limited bearing capacity and is not suitable for a soft foundation with lower bearing capacity (the shear strength of non-drainage is less than 15 kPa). According to the invention, the composite geotechnical packaging body is formed by combining the tire strips with the geotechnical cloth, so that the technical advantage of high tensile strength of the tire strips is fully exerted, the radial deformation of the internal filler is effectively restrained, the integral working performance of the pile foundation is increased, and the stability is improved.

(2) The variable cross-section is arranged, so that the contact area between the pile foundation and the soil around the pile is increased, the shear strength and the compressive bearing performance of the soil around the pile are fully exerted, the integral bearing capacity of the pile foundation is obviously improved, the pile length, the pile spacing and the pile diameter in actual engineering can be effectively reduced, the engineering cost is reduced, the construction process is simplified, and the engineering construction time is shortened. Meanwhile, the shearing resistance at the pile top position can be improved, and the anti-sliding constraint force of the embankment sloping field is increased.

(3) Compared with the existing pile-geogrid composite foundation, the invention uses the waste tire with higher tensile strength, and further enhances the overall working performance of the pile-soil composite foundation by arranging the connection between the tire grid and the pile foundation, and the bearing capacity and the stability of the foundation are obviously improved.

(4) Except for the geotextile and the connecting member used in the composite geotechnical packaging body, all raw materials such as waste tires, solid waste fillers and the like are industrial solid waste materials, so that the use of sandstone materials and geogrids can be obviously reduced, a large amount of industrial solid waste materials can be consumed, the engineering construction cost is effectively reduced, the environmental pollution and land occupation caused by the stockpiling of a large amount of industrial solid waste materials are solved, and the composite geotechnical packaging body has obvious environmental significance and social significance.

(5) The waste tire can be directly used for manufacturing a composite geotechnical packaging body after being simply cut and processed, the tire crown is used for manufacturing a reinforced material, the tire wall is used for manufacturing a grid material, the problems of energy consumption, solid waste residue and the like generated in the secondary processing process are effectively reduced, the solid waste filler can be directly filled, and the secondary processing cost of the solid waste comprehensive utilization is effectively reduced.

(6) The method is simple in operation method, low in cost, universal and easy for large-scale production and engineering application.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification, illustrate exemplary embodiments of the invention and together with the description serve to explain the invention and not to limit the invention.

FIG. 1 is a schematic view of a waste tire pile of the present invention in its entirety with a variable cross-section;

FIG. 2 is an enlarged view of a portion of a variable cross-section post of the present invention;

FIG. 3 illustrates a tire strip attachment of the present invention;

FIG. 4 is a drawing illustrating a construction step of a variable cross-section waste tire pile composite foundation according to the present invention;

FIG. 5 is a schematic view of a post-forming scrap tire and scrap pile composite foundation of the present invention;

the composite geotechnical packaging material comprises 1 radial tire strips, 2 axial tire strips, 3 pressing geotextile, 4 variable cross-section widening tire strip, 5 connecting components, 6 variable cross-section sections, 7 steel backing plates, 8 high-strength pre-tightening bolts, 9 improved epoxy resin glue, 10 composite geotechnical packaging bodies, 11 sleeves, 12 steel wire ropes, 13 solid waste fillers, 14 rammers, 15 grid layers, 16 cushion layers, 17 waste tire sidewalls, 18 waste tire discrete pile tops, 19 connecting tire strips.

Detailed Description

It is to be understood that the following detailed description is exemplary and is intended to provide further explanation of the invention as claimed. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

A variable cross-section waste tire pile composite foundation mainly comprises waste tire strips, pressing geotextile, smelting waste residues or building garbage or tailings and other solid waste fillers.

In some embodiments, the strip of junked tires is formed by direct excision of the sidewalls from the junked tires or by cutting the crown along tread grooves, has a thickness of not less than 1.5cm, a compressive strength of not less than 20Mpa, and an ultimate load elongation of not more than 20%, wherein the radial strip width is not less than 7 cm.

In some embodiments, the tire strip is divided into a radial tire strip and an axial tire strip according to the pile direction, the radial tire strip and the axial tire strip are crossed vertically, the axial tire strip is arranged on the inner side, the radial tire strip is arranged on the outer side, and the crossed position of the radial tire strip and the axial tire strip is bonded through modified epoxy resin glue and fastened by combining a pre-tightening bolt and a square rigid backing plate. The diameter of the bolt is not less than 0.8cm, and the length of the bolt is 3 cm. The thickness of the square rigid backing plate is 0.3-0.5cm, and the length and the width are respectively 5cm multiplied by 5 cm. After the bolt and the rigid backing plate are pre-tightened and anchored, anticorrosion treatment is carried out, such as spraying anticorrosion paint or sealing by epoxy resin. After connection, the longitudinal and axial tire strips are connected to form a tire strip reinforcement cage structure.

In some embodiments, the tire strip reinforcement body is divided into a conventional section and a variable section, the distribution depth of the conventional section is 1-1.5m, the distribution depth of the variable section is the same as that of the conventional section, but the total number of the variable section is not more than 5, the diameter of the maximum section is 2 times of that of the conventional section, and the conventional section and the variable section are in equidistant transition. The radial tire strips with the conventional section segments are of an integral annular structure formed by directly cutting off the tire walls from waste tires, so that the inner diameter of the pile body is close to the inner diameter of the tire after the tire walls are cut off, and the distance between the upper radial tire strip and the lower radial tire strip is 10-15 cm. The variable-section radial tire strip is formed by transversely cutting the annular structure into strips, and the strips are connected through the end parts to form large-diameter annular structures with different circumferences. The vertical distance between the radial tire strips of the variable section is not more than 10cm, and the widened tire strips are adopted at the maximum diameter of the variable section.

In some embodiments, the axial tire strips are spaced from 10-15cm from the left to the right. Along the setting direction, two adjacent axial tire strips and the radial tire strips of the variable cross-section are connected in a manner of combining cementing and pre-tightening bolts with a square rigid backing plate and the like, the length of single-side cementing is not less than 10cm, the number of the bolts is 4, the diameter of each bolt is not less than 1cm, and the length of each bolt is 3 cm. The length and width of the rigid cushion plate are the same as the width of the axial tire strip, and the thickness of the square rigid cushion plate is not less than 0.4 cm.

In some embodiments, the press geotextile is a water-permeable mud-impermeable material, has a tensile strength of not less than 1MPa, is formed into an annular wrapping shape by double-layer sewing with 209 sewing threads, and has a sewing lap width of not less than 20cm and a seam distance of not more than 2 cm. And the pressing geotextile is nailed on the inner wall of the axial tire strip through the drawing pin to form the composite geotextile packaging body.

In some embodiments, the filling material inside the pile body can be solid waste materials such as smelting waste residues or construction waste or tailings, and the solid waste materials have good chemical stability and do not pollute underground water. The particle size range of the solid waste material is between 0 and 5cm, the solid waste material is filled into the composite geotechnical packaging body in a layered mode, and the thickness of each layer is not more than 1.5 m. After filling, the mixture is tamped and compacted by a tamping hammer, the tamping energy can be not less than 20 kN.m by one stroke, and the total tamping energy can be not less than 100 kN.m.

A variable cross-section waste tire pile composite foundation and a construction process thereof further comprise the following construction processes:

preparation before construction:

1. firstly, an indoor model test or an on-site single pile loading test of the variable cross-section waste tire pile is carried out, the change rule between the bearing capacity of the variable cross-section waste tire pile and the pile diameter, the pile length, the variable cross-section quantity and the characteristics of foundation soil is determined, and the key parameters such as the optimal ramming energy and the ramming times of a solid waste material chamber filled with smelting waste residues, construction waste, tailings and the like of the variable cross-section waste tire pile are researched.

2. And determining the bearing capacity of the reinforced pile-soil composite foundation according to calculation, selecting proper pile diameter, pile length, pile spacing, variable cross section quantity, filler type and the like according to the determined bearing capacity of the foundation and considering construction difficulty and economy, and determining key parameters such as optimal ramming energy (ramming frequency, hammer weight and lifting height).

3. And selecting waste tires with proper sizes by referring to the pile diameter parameters in the previous step, and performing a tire strip limit drawing test to ensure that the tensile strength meets the construction requirements. And carrying out secondary processing such as cutting, binding, connecting and the like on the tire strips and the geotextile according to the designed size to form the composite geotechnical packaging body.

The construction process comprises the following steps:

1. and (6) drilling. The drilling machine can be installed according to a preset position in a drilling or vibrating hole forming mode, the deviation is not larger than 1cm, the drilling diameter is larger than the preset pile diameter by 8cm, the thickness of a sleeve is reserved, the drilling depth exceeds the preset pile length by 0.5m, and the deviation of the angle between the drilling hole and the vertical direction is not more than 1 degree.

2. And (5) installing a sleeve. After drilling is finished, a sleeve is placed downwards through a drilling machine, the inner diameter of the sleeve is the same as the outer diameter of the conventional section tire strip reinforcement cage, the wall thickness of the sleeve is 1-2cm, and the upper end and the lower end of the sleeve are not sealed. Before the sleeve is lowered, the composite geotechnical packaging body is installed in the sleeve and is lowered into the drilled hole together with the sleeve. After the sleeve is placed, the composite geotechnical packaging body is temporarily hoisted on the drilling machine support through the steel wire rope so as to prevent the composite geotechnical packaging body from falling when the solid waste filler is filled and vibrated.

3. Filling the filler. And after the sleeve is installed, filling solid waste materials into the composite geotechnical packaging body, stopping filling when the filling height reaches the bottom surface (from the bottom) of the section 1 variable cross section (from the bottom), and lifting the sleeve upwards to the top surface of the solid waste materials.

4. And (5) vibrating and compacting the conventional section. And after the filling of the 1 st layer of solid waste material is finished, tamping and compacting are carried out, a rammer is hoisted by a drilling machine, the weight of the rammer is 1-2 tons, the diameter of the rammer is smaller than the inner diameter of the composite geotechnical packaging body, the hoisting height is not more than 2m, the tamping energy and the tamping times are determined according to early-stage tests to carry out tamping and compacting, the single-stroke tamping energy is not less than 20 kN.m, and the total tamping energy is not less than 100 kN.m.

5. Vibrating and compacting the section with variable cross section. And after the compaction of the section 1 conventional section is finished, continuously filling solid waste filler to the top of the section 1 variable section, and then lifting the sleeve upwards to the top surface of the filler for vibration compaction. The mode of tamping, compacting and tamping is the same as that of the conventional section, but the total tamping energy should be 1.5 times that of the conventional section.

6. And repeating the steps 3-5 until the pile foundation is filled to the designed elevation.

7. And laying a cushion layer. After the pile foundation construction is finished, a top cushion layer is laid, and the cushion layer can be made of steel slag, tailings, building garbage and broken stones. The thickness of the cushion layer is not less than 30cm, a layer of grid reinforcement material formed by manufacturing waste tire walls and connecting tire strips is arranged on the top of the cushion layer and the top of the pile foundation and is connected with the longitudinal tire strips of the reinforcement cage, the connection mode is the same as that of the above connection mode, and the grid is used for fully paving the whole reinforced foundation. Or tyre strips can be adopted to manufacture a grid structure, the width of the tyre strips is consistent with that of axial strips of the pile tyre strip reinforcement cage, and the distance between the tyre strips forming the grid is 10-15 cm.

The present invention is described in further detail below with reference to specific examples, which are intended to be illustrative of the invention and not limiting.

As shown in fig. 1, the variable cross-section waste tire pile composite foundation mainly comprises a waste tire strip 1/2, a pressing geotextile 3 and solid waste fillers 13 such as smelting waste residues or construction waste or tailings.

In some embodiments, the scrap tire strip 1/2 is formed by directly cutting off the sidewalls 17 of the scrap tire or by cutting the tire crown along tread grooves, has a thickness of not less than 1.5cm, a compressive strength of not less than 20Mpa, and an ultimate load elongation of not more than 20%, wherein the radial strip width is not less than 7 cm.

In some specific embodiments, the tire strip is divided into two types of radial 1 and axial 2 according to the pile direction, the radial tire strip 1 and the axial tire strip 2 are crossed vertically, the axial tire strip 2 is arranged on the inner side, the radial tire strip 1 is arranged on the outer side, the crossed position of the two is bonded through modified epoxy resin glue 9, and the two are fastened through a pre-tightening bolt 8 and a square rigid backing plate 7. The bolt 8 has a diameter of not less than 0.8cm and a length of 3 cm. The thickness of the square rigid backing plate 7 is 0.3-0.5cm, and the length and the width are respectively 5cm multiplied by 5 cm. After the bolt 8 and the rigid backing plate 7 are pre-tightened and anchored, corrosion prevention treatment is carried out, such as spraying corrosion prevention paint or sealing by epoxy resin. After connection, the longitudinal 1 and axial 2 tire strips are connected to form a pile tire strip reinforcement cage structure.

In some specific embodiments, the tire strip reinforcement body is divided into a conventional section and a variable section 6, the distribution depth of the conventional section is 1-1.5m, the distribution depth of the variable section 6 is the same as that of the conventional section, the total number of the variable section 6 is not more than 5, the diameter of the maximum section is 2 times of that of the conventional section, and the conventional section and the variable section are in equidistant transition. The radial tire strip 1 with the conventional section segment is of an integral annular structure formed by directly cutting off the tire wall by waste tires, so that the inner diameter of a pile body is close to the inner diameter of the tire after the tire wall is cut off, and the distance between the upper radial tire strip 1 and the lower radial tire strip 1 is 10-15 cm. The radial tire strip of the variable cross section 6 is transversely cut into strips by the annular structure, and then the strips are connected with each other at the end parts to form large-diameter annular structures with different circumferences. The distance between the variable section 6 and the radial tire strip 1 is not more than 10cm, and the widened tire strip 4 is adopted at the maximum diameter of the variable section.

In some embodiments, the axial tire strips 2 are spaced apart from one another by 10-15 cm. Along the arrangement direction, two adjacent axial tire strips 2 and two adjacent radial tire strips 1 of the variable cross section 6 are connected in a manner of combining a cementing 9 and a pre-tightening bolt 8 with a square rigid backing plate 7 and the like, the length of single-side cementing is not less than 10cm, the number of the bolts 8 is 4, the diameter of each bolt 8 is not less than 1cm, and the length of each bolt is 3 cm. The length and width of the rigid cushion plate 7 are the same as the width of the axial tire strip 2, and the thickness of the square rigid cushion plate 7 is not less than 0.4 cm.

In some embodiments, the press geotextile 3 is a water-permeable mud-impermeable material, has a tensile strength of not less than 1MPa, and is formed into an annular wrapping shape by double-layer sewing with 209 sewing threads, wherein the sewing lap width is not less than 20cm, and the seam distance is not more than 2 cm. And the pressing geotextile is nailed on the inner wall of the axial tire strip 2 through the drawing pin to form the composite geotextile packaging body 10.

In some embodiments, the filling material inside the pile body can be solid waste material 13 such as smelting waste or construction waste or tailings, and the solid waste material has good chemical stability and does not pollute underground water. The particle size range of the solid waste material 13 is between 0 and 5cm, and the solid waste material is filled into the composite geotechnical packaging body 10 in a layered mode, wherein the thickness of each layer is not more than 1.5 m. After filling, the mixture is compacted by 14 times of ramming by a rammer, the ramming energy of one stroke can be not less than 20 kN.m, and the total ramming energy can be not less than 100 kN.m.

A variable cross-section waste tire pile composite foundation and a construction process thereof further comprise the following construction processes:

the test method comprises the following steps:

step 1, firstly, carrying out an indoor model test or an on-site single pile loading test on the variable cross-section waste tire pile, determining the change rule between the bearing capacity of the variable cross-section waste tire pile and the pile diameter, the pile length, the variable cross-section quantity and the characteristics of foundation soil, and researching the optimal ramming energy, ramming times and other key parameters of the variable cross-section waste tire pile for filling smelting waste residues, construction wastes, tailings and other solid waste materials in 13 rooms.

And 2, determining the bearing capacity of the reinforced pile-soil composite foundation according to calculation, selecting proper pile diameter, pile length, pile spacing, variable cross section quantity, filler type and the like according to the determined bearing capacity of the foundation and considering construction difficulty and economy, and determining key parameters such as optimal ramming energy (ramming frequency, hammer weight and lifting height).

And 3, selecting waste tires with proper sizes by referring to the pile diameter parameters in the previous step, and performing an ultimate drawing test on the tire strips 1/2 to ensure that the tensile strength meets the construction requirements. And performing secondary processing such as cutting, binding and connecting on the tire strips 1/2 and the geotextile 3 according to the designed size to form the composite geotextile packaging body 10.

And 3, drilling. The drilling machine can be installed according to a preset position in a drilling or vibrating hole forming mode, the deviation is not larger than 1cm, the drilling diameter is larger than the preset pile diameter by 8cm, the thickness of the sleeve 11 is reserved, the drilling depth is larger than the preset pile length by 0.5m, and the deviation of the drilling angle and the vertical direction is not larger than 1 degree.

And 4, installing the sleeve 11. After drilling is finished, the sleeve 11 is placed downwards through a drilling machine, the inner diameter of the sleeve 11 is the same as the outer diameter of the conventional section tire strip 1/2 reinforced cage, the thickness of the sleeve wall 11 is 1-2cm, and the upper end and the lower end of the sleeve wall are not sealed. Before the sleeve 11 is lowered, the composite geotechnical packaging body 10 is installed in the sleeve 11 and is lowered into the drilled hole together with the sleeve 11. After the sleeve 11 is lowered, the composite geotechnical packaging body 10 is temporarily hung on a drill rig bracket through a steel wire rope 12 so as to prevent the composite geotechnical packaging body 10 from falling when the solid waste filler 13 is filled and vibrated.

And 5, filling the filler. After the sleeve 11 is installed, solid waste materials 13 are filled into the composite geotechnical packaging body 10, when the filling height reaches the bottom surface (from the bottom) of the section 1 variable cross section (from the bottom) (filling height is 1.0-1.5m), filling is stopped, and the sleeve 11 is lifted upwards to the top surface of the solid waste materials 13.

And 6, vibrating and compacting the conventional section. And after the 1 st layer of solid waste material 13 is filled, tamping and compacting are carried out, a drilling machine is used for hoisting a rammer 14, the weight of the rammer 14 is 1-2 tons, the diameter of the hammer is smaller than the inner diameter of the composite geotechnical packaging body 10, the hoisting height is not more than 2m, the ramming energy and the ramming frequency are determined according to an early test for tamping and compacting, the single-shot ramming energy is not less than 20 kN.m, and the total ramming energy is not less than 100 kN.m.

And 7, vibrating and compacting the variable section 6. And after the compaction of the section 1 with the conventional section is finished, continuously filling solid waste filler 13 to the top of the section 1 with the variable section, and then lifting the sleeve 11 upwards to the top surface of the filler 13 for vibration compaction. The mode of tamping, compacting and tamping is the same as that of the conventional section, but the total tamping energy should be 1.5 times that of the conventional section.

And 8, repeating the steps 3-5 until the pile foundation is filled to the designed elevation.

And 9, paving a cushion layer 16. After the pile foundation construction is finished, a top cushion layer 16 is laid, and the cushion layer 16 can be made of steel slag, tailings, building garbage and broken stones. The thickness of the cushion layer 16 is not less than 30cm, a layer of grid reinforcement material made of waste tire walls 17 and connecting tire strips 19 is arranged on the cushion layer 16 and the pile foundation top 18 and is connected with the longitudinal tire strips 1/2 of the reinforcement cage, the connection mode is the same as the connection mode, and the grid is fully paved on the whole reinforced foundation. The tire strips 1/2 can also be used for manufacturing a grid structure, the width of each tire strip 1/2 is consistent with that of the axial strips 2 of the pile tire strip reinforcement cage, and the distance between the tire strips forming the grid is 10-15 cm.

It should be noted that the above-mentioned embodiments are only preferred embodiments of the present invention, and the present invention is not limited thereto, and although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that modifications and equivalents can be made in the technical solutions described in the foregoing embodiments, or equivalents thereof. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.