阅读说明：本技术 一种抗上拱螺纹桩结构及其设计和施工方法 (Anti-upwarp threaded pile structure and design and construction method thereof ) 是由 周和祥 付铭川 李宁 周成 吴沛沛 胡超 曾永红 龚建辉 肖昌睿 陈伟志 周川滨 于 2020-06-29 设计创作，主要内容包括：本发明涉及岩土工程领域,特别是一种抗上拱螺纹桩结构及其设计和施工方法,其中螺纹桩结构包括螺纹桩,所述螺纹桩的上部具有等直径段,所述螺纹桩的下部具有螺纹段,所述螺纹段的外壁上具有螺纹,所述等直径段外侧套设有双层钢护筒,所述双层钢护筒包括内层钢护筒和外层钢护筒,所述内层钢护筒与所述外层钢护筒能够相对移动。本申请所述的一种抗上拱螺纹桩结构,能够增大抗拔桩(选用螺纹桩为抗拔桩)的抗上拱能力,不仅满足软岩深路堑条件下使用,而且相比于常规的等直径抗拔桩来说,在相同的抗上拱能力的条件下,规格更小,经济性更高。(The invention relates to the field of geotechnical engineering, in particular to an anti-upwarp threaded pile structure and a design and construction method thereof, wherein the threaded pile structure comprises a threaded pile, the upper part of the threaded pile is provided with a constant-diameter section, the lower part of the threaded pile is provided with a threaded section, threads are arranged on the outer wall of the threaded section, a double-layer steel casing is sleeved on the outer side of the constant-diameter section, the double-layer steel casing comprises an inner-layer steel casing and an outer-layer steel casing, and the inner-layer steel casing and the outer-layer steel casing can move relatively. This application an anti screw pile structure that arches, can increase the anti ability of arching of uplift (select for screw pile to be uplift) not only satisfy and use under the dark cutting condition of soft rock, compare in conventional equal diameter uplift moreover, under the same anti condition of arching ability, the specification is littleer, economic nature is higher.)

1. The utility model provides an anti-upwarp screw thread pile structure, its characterized in that, includes screw thread pile (2), the upper portion of screw thread pile (2) has equal diameter section (21), the lower part of screw thread pile (2) has screw thread section (22), screw thread has on the outer wall of screw thread section (22), equal diameter section (21) outside cover is equipped with double-deck steel and protects a section of thick bamboo (1), double-deck steel protects a section of thick bamboo (1) and includes that inlayer steel protects a section of thick bamboo and outer steel and protects a section of thick bamboo, inlayer steel protect a section of thick bamboo with outer steel protects a section of thick bamboo and can relative movement.

2. An anti-upwarp screw pile structure according to claim 1, characterized in that the axial length of the double-layer steel casing (1) is matched with the thickness of the upwarp deformation zone (3), and the axial length of the equal-diameter section (21) along the axial direction thereof is matched with the axial length of the double-layer steel casing (1).

3. A design method for an anti-upwarp thread pile structure according to claim 1 or 2, characterized by comprising the steps of,

A1. presetting the structural size of the screw thread pile (2), and calculating the self weight G of the screw thread pile (2) according to the structural size_pAnd the standard value T of the vertical uplift limit bearing capacity of the single pile of the screw pile (2)_uk；

A2. The self weight G of the screw thread pile (2)_pAnd the standard value T of the vertical uplift limit bearing capacity of the single pile of the screw pile (2)_ukCalculating the characteristic value R of the vertical uplift bearing capacity of the single pile of the threaded pile (2)_a；

A3: according to the characteristic value R of the vertical uplift bearing capacity of the single pile of the threaded pile (2)_aAdjusting the structural size of the threaded pile (2) until the calculated characteristic value R of the vertical uplift bearing capacity of the single pile of the threaded pile (2)_aAnd the anti-pulling requirement is met, and the final structural size of the threaded pile (2) is obtained.

4. A design method according to claim 3, characterized in that when calculating the standard value of the single-pile vertical uplift limit bearing capacity of the threaded pile (2), the side resistance of the equal-diameter section (21) is excluded according to the side resistance of the threaded section (22).

5. The design method according to claim 4, wherein the standard value of the single-pile vertical pullout limit bearing capacity of the screw pile (2) is:

T_uk＝u∑λβq_sikl_i

in the formula: t is_ukThe standard value of the vertical uplift ultimate bearing capacity of the single pile of the threaded pile (2), kN; q. q.s_sikThe standard value of the resistance of the ultimate side of the dry-operation drilled pile is kPa, lambda is the resistance coefficient of the pulling resistance, β is the enhancement coefficient of the standard value of the equivalent ultimate side resistance of the pile body of the screw pile (2) relative to the standard value of the resistance of the ultimate side of the dry-operation drilled pile, l_iThe thickness m of the ith layer of soil through which the thread section (22) passes.

6. The design method according to claim 5, wherein the single-pile vertical uplift bearing capacity characteristic values of the threaded pile (2) are in particular:

R_a＝T_uk/K+G_p

in the formula: r_aThe characteristic value kN of the vertical uplift bearing capacity of the single pile of the threaded pile (2); k is a safety factor; t is_ukThe standard value of the vertical uplift ultimate bearing capacity of the single pile of the threaded pile (2), kN; g_pThe self weight of the screw thread pile (2) is kN.

7. A construction method for forming an anti-upwarp thread pile structure according to claim 1 or 2, wherein the construction method comprises the following steps based on a drilling machine (5), the drilling machine (5) comprises an auger stem (51), a conveying channel for conveying concrete is arranged inside the auger stem (51) along the length, and an outlet communicated with the conveying channel is arranged at the position of a drill head (52) of the auger stem (51):

s1, sinking the double-layer steel casing (1) to a preset position in an upper arch deformation area (3);

s2, starting the drilling machine (5), enabling the auger stem (51) to rotate in the forward direction, and conducting drilling construction, wherein the auger stem (51) penetrates through the upper arch deformation region (3) and extends into the stable region (4) until the preset depth of the thread section (22) is reached, and then stopping drilling to form a pile hole for forming the thread pile (2);

s3, the auger stem (51) rotates reversely and returns, and meanwhile concrete is continuously pumped to the drill bit (52) through the conveying channel and is filled into the pile hole;

s4, when the drill bit (52) reaches the interface of the upper arch deformation area (3) and the stable area (4), the auger stem (51) rotates forwards and returns, and concrete is conveyed into the pile hole continuously until the pile hole is completely filled with the concrete;

s5, sinking the reinforcement cage (53) of the threaded pile (2) into the concrete in the pile hole until the reinforcement cage reaches a preset position, and forming the integrally poured threaded pile (2) after the concrete is solidified.

8. A method of construction according to claim 7 wherein the auger (51) is rotated in reverse and during the return stroke the drill bit (52) is brought into contact with the concrete in the pile bore.

9. A construction method according to claim 7, wherein there is a gap between the reinforcement cage (53) and the inner wall of the pile hole.

10. A construction method according to any one of claims 7-9, wherein, based on the drilling machine (5) comprising a vibrating pipe, in step S5, the reinforcement cage (53) of the screw pile (2) is sleeved into the vibrating pipe and the reinforcement cage (53) is vibrated to sink into the concrete in the pile hole.

Technical Field

The invention relates to the field of geotechnical engineering, in particular to an anti-upwarp threaded pile structure and a design and construction method thereof.

Background

The soft rock generally has strong unloading creep and water swelling properties, and when a ballastless track passes through a soft rock region in a deep cutting mode, the risk of arching diseases on a roadbed structure is high under the dual effects of excavation unloading and water environment change.

In order to ensure the operation safety of the high-speed railway, an uplift pile structure is usually adopted to control the deformation of an upper arch of a roadbed at present.

However, as shown in fig. 1, under the condition of a soft rock deep cutting, an upwarp deformation area 3 is stored in a certain depth below a roadbed, the lower part of the upwarp deformation area 3 is a stable area 4, and the rock soil body in the upwarp deformation area 3 can generate upwarp deformation, so that the uplift resistance is applied to the uplift pile, and the upwarp resistance of the uplift pile is reduced.

In addition, conventional equal diameter piles provide relatively limited side resistance, resulting in longer pile shaft, larger cross-section and less economical design.

Disclosure of Invention

The invention aims to: aiming at the problems that in the prior art, the uplift resistance of uplift piles can be reduced by rock-soil under the condition of soft rock deep cutting, and the conventional equal-diameter uplift piles provide relatively limited pile side resistance, so that the designed pile body is longer, the section is larger, and the economy is poorer, the design method of the uplift resistant threaded pile structure and the construction method of the uplift resistant threaded pile structure are provided, the uplift resistance of the uplift piles can be increased, the soft rock deep cutting condition is met, and compared with the conventional equal-diameter uplift piles, the specifications are smaller and the economy is higher under the condition of the same uplift resistance.

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

the utility model provides an anti-upwarp screw thread pile structure, includes screw thread pile, screw thread pile's upper portion has the equal diameter section, screw thread pile's lower part has the screw thread section, the screw thread has on the outer wall of screw thread section, equal diameter section outside cover is equipped with double-deck steel and protects a section of thick bamboo, double-deck steel protects a section of thick bamboo and includes that the inlayer steel protects a section of thick bamboo and outer steel and protects a section of thick bamboo, the inlayer steel protect a section of thick bamboo with outer steel protects a section of thick bamboo can.

An anti screw thread pile structure that arches, including double-deck steel retaining cylinder, screw thread pile, the screw thread pile divide into diameter sections such as upper portion, lower part screw thread section, and double-deck steel retaining cylinder includes that inlayer steel retaining cylinder and outer steel retaining cylinder, and inlayer steel retaining cylinder and outer steel retaining cylinder can relative movement, and when the construction, the screw thread section stretches into in the stable area of ground, and the diameter sections such as equal diameter is located the deformation zone that arches of ground, diameter sections such as screw thread pile are equipped with double-deck steel retaining cylinder outward, can effectively eliminate the adverse side resistance influence of screw thread pile structure at the deformation zone that arches, and diameter sections such as upper portion adoption enable the pile body and double-deck steel retaining cylinder's inlayer steel retaining cylinder to combine inseparabler to improve pile body bulk strength, the lower part adopts the screw thread section can increase the side resistance of pile body in the stable area, thereby reinforcing screw thread pile structure's whole resistance to.

To sum up, this application an anti screw pile structure that arches can increase the anti ability of arching of uplift (select the screw pile for use to be the uplift) not only satisfy and use under the dark cutting condition of soft rock, compare in the equal diameter uplift of conventional moreover, under the same condition of anti ability of arching, the specification is littleer, and economic nature is higher.

Preferably, the axial length of the double-layer steel casing is matched with the thickness of the upper arch deformation area, and the axial length of the equal-diameter section is matched with the axial length of the double-layer steel casing along the axial length of the equal-diameter section, so that the adverse side resistance influence of the threaded pile structure in the upper arch deformation area is completely eliminated.

The application also discloses a design method for the anti-upwarp thread pile structure, which comprises the following steps,

A1. presetting the structural size of the threaded pile, and calculating the self weight G of the threaded pile according to the structural size_pAnd the standard value T of the vertical uplift limit bearing capacity of the single pile of the threaded pile_uk；

A2. The dead weight G of the screw pile_pAnd the standard value T of the vertical uplift limit bearing capacity of the single pile of the threaded pile_ukCalculating the characteristic value R of the vertical uplift bearing capacity of the single pile of the threaded pile_a。

A3: according to the characteristic value R of the vertical uplift bearing capacity of the single pile of the threaded pile_aAdjusting the structural size of the threaded pile until the calculated characteristic value R of the vertical uplift bearing capacity of the single pile of the threaded pile is obtained_aAnd the anti-pulling requirement of the threaded pile is met, and the final structural size of the threaded pile is obtained.

According to the design method for the anti-arching threaded pile structure, the structural size of the threaded pile is preset according to experience, the dead weight of the threaded pile and the single-pile vertical uplift limit bearing capacity standard value of the threaded pile are calculated according to the dead weight of the threaded pile, the single-pile vertical uplift bearing capacity characteristic value of the threaded pile is further calculated, and then the structural size of the threaded pile is adjusted according to whether the single-pile vertical uplift bearing capacity characteristic value of the threaded pile meets the uplift requirement of the threaded pile or not, so that the final structural size of the threaded pile is obtained.

Preferably, when the standard value of the vertical uplift limit bearing capacity of the single pile of the threaded pile is calculated, the side resistance of the equal-diameter section is eliminated according to the side resistance of the threaded section.

And when the standard value of the vertical uplift ultimate bearing capacity of the single pile of the threaded pile is calculated, the side resistance of the equal-diameter section at the upper part of the threaded pile is ignored, and only the side resistance of the threaded pile at the lower part of the threaded pile is considered, so that the calculation is more deviated to safety.

Preferably, the standard value of the single-pile vertical uplift ultimate bearing capacity of the threaded pile is as follows:

T_uk＝u∑λβq_sikl_i

in the formula: t is_ukThe standard value of the vertical uplift ultimate bearing capacity of the single pile of the threaded pile is kN; q. q.s_sikThe method comprises the steps of taking a standard value of resistance at the extreme side of a dry-operation drilled pile, kPa, lambda as a pulling resistance coefficient, β as an enhancement coefficient of the standard value of the equivalent extreme side resistance of a pile body of the threaded pile relative to the standard value of the resistance at the extreme side of the dry-operation drilled pile, taking a high value when soil at the side of the threaded pile is mainly sandy soil and taking a low value when soil at the side of the threaded pile is mainly cohesive soil, and l_iThe thickness m of the ith layer of soil through which the thread section penetrates.

Preferably, the characteristic value of the vertical uplift bearing capacity of the single pile of the threaded pile is as follows:

R_a＝T_uk/K+G_p

in the formula: r_aThe characteristic value of the vertical uplift bearing capacity of the single pile of the threaded pile is kN; k is a safety coefficient, and K is 2; t is_ukThe standard value of the vertical uplift ultimate bearing capacity of the single pile of the threaded pile is kN; g_pThe self weight of the screw pile is kN.

The application also discloses a construction method for forming the anti-upwarp threaded pile structure, based on a drilling machine, the drilling machine comprises an auger stem, a conveying channel for conveying concrete is arranged inside the auger stem along the length, an outlet communicated with the conveying channel is arranged at the drill bit part of the auger stem, and the construction method comprises the following steps:

s1, sinking the double-layer steel casing to a preset position in an upper arch deformation area;

s2, starting the drilling machine, enabling the auger stem to rotate in the forward direction, performing drilling construction, enabling the auger stem to penetrate through the upper arch deformation region and extend into the stable region, stopping drilling until the preset depth of the thread section is reached, and forming a pile hole for forming the thread pile;

s3, the spiral drill rod rotates reversely and returns, meanwhile, concrete is continuously pumped to the drill bit through the conveying channel and is filled into the pile hole;

s4, when the drill bit reaches the boundary surface of the upper arch deformation area and the stable area, the spiral drill rod rotates forwards and returns, and concrete is conveyed into the pile hole continuously until the pile hole is completely filled with the concrete;

s5, sinking the reinforcement cage of the threaded pile into the concrete in the pile hole until the reinforcement cage reaches a preset position, and forming the integrally poured threaded pile after the concrete is solidified.

The application a construction method for form this application anti-upwarp screw thread pile structure, based on the rig, through the corotation and the upset of auger stem on the rig to can bore the screw hole in the lower part, the equal diameter hole that turns to on upper portion, thereby guaranteed to drill and filled back formation equal diameter section and screw thread section, later sink the steel reinforcement cage in the downthehole concrete of stake, finally form the screw thread pile of the integrative pouring that meets the requirements, the construction is simple, whole work progress can both be with the help of rig machinery, labour saving and time saving, reduction of erection time, reduction of construction cost.

Preferably, the auger shaft rotates in the reverse direction and during the return stroke, the drill bit contacts the concrete in the pile hole. So as to avoid the condition that the pile body clamps mud or breaks the pile, and influence the pile forming effect.

Preferably, a gap is formed between the reinforcement cage and the inner wall of the pile hole.

If the steel reinforcement cage inserts the inner wall, can destroy the screw thread stake hole that the drilling formed, cause the influence to the screw thread stake quality after pouring, so the steel reinforcement cage with have the clearance between the inner wall in stake hole to avoid the steel reinforcement cage to insert the inner wall.

Preferably, the drilling machine comprises a vibrating tube, and in step S5, the reinforcement cage of the screw pile is sleeved into the vibrating tube and is vibrated and sunk into the concrete in the pile hole.

In summary, due to the adoption of the technical scheme, the invention has the beneficial effects that:

1. this application an anti screw pile structure that arches, can increase the anti ability of arching of uplift (select for screw pile to be uplift) not only satisfy and use under the dark cutting condition of soft rock, compare in conventional equal diameter uplift moreover, under the same anti condition of arching ability, the specification is littleer, economic nature is higher.

2. An anti screw thread pile structure that arches, the axial length of a double-deck steel protects a section of thick bamboo and the thickness looks adaptation of the deformation zone that arches upward, when the axial with of diameter section length the axial length looks adaptation of a double-deck steel protects to eliminate screw thread pile structure completely and arch the adverse side resistance influence in deformation zone.

3. According to the design method for the anti-upwarp threaded pile structure, the structural size of the threaded pile is preset according to experience, calculating the dead weight of the threaded pile and the standard value of the vertical uplift ultimate bearing capacity of the single pile of the threaded pile, further calculating the characteristic value of the vertical uplift bearing capacity of the single pile of the threaded pile, and then adjusting the structural size of the threaded pile according to whether the characteristic value of the vertical uplift bearing capacity of the single pile of the threaded pile meets the uplift requirement of the threaded pile, so as to obtain the final structural size of the threaded pile, the method can scientifically and reasonably develop the uplift resistance design of the anti-arching threaded pile structure, has clear mechanical principle, clear derivation thought and simple calculation process, ensures the stress safety of the structure of the invention, and provides reliable basis for engineering design calculation.

4. A design method that is used for this application anti-upwarp screw thread pile structure, when calculating the vertical resistance to plucking limit bearing capacity standard value of single pile of screw thread pile, neglect the side resistance of screw thread pile upper portion equal diameter section, only consider the side resistance of screw thread pile lower part screw thread pile, make the calculation more to safety.

5. The application a be used for forming the application the construction method of anti-upwarp screw thread pile structure, based on the rig, through the corotation and the upset of auger stem on the rig to can bore the screw hole in the lower part, the equal diameter hole that turns to on upper portion, thereby guaranteed that drilling fills after diameter section and screw thread section such as formation, later sink the steel reinforcement cage in the downthehole concrete of stake, finally form the screw thread pile of integrative pouring that meets the requirements, the construction is simple, whole work progress can both be with the help of rig machinery, labour saving and time saving, reduction of erection time, reduction of construction cost.

Drawings

Fig. 1 is a schematic structural view of a soft rock foundation of the prior art.

Fig. 2 is a schematic structural view of an anti-upwarp thread pile structure of the invention.

Fig. 3 is a schematic construction diagram of step S1 in the construction method of the present invention.

Fig. 4 is a schematic construction diagram of step S2 in the construction method of the present invention.

Fig. 5 is a schematic construction diagram of step S3 in the construction method of the present invention.

Fig. 6 is a schematic construction diagram of step S4 in the construction method of the present invention.

Fig. 7 is a schematic construction diagram of step S5 in the construction method of the present invention.

Icon: 1-double-layer steel casing; 2-screw thread pile; 21-equal diameter section; 22-a threaded section; 3-an upwarp deformation zone; 4-a stable region; 5-a drilling machine; 51-auger stem; 52-a drill bit; 53-steel reinforcement cage.

Detailed Description

The present invention will be described in detail below with reference to the accompanying drawings.

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.