阅读说明：本技术 一种砂卵石地质变截面螺杆桩施工工艺 (Sand-pebble geological variable-section screw pile construction process ) 是由 张涛 张永伟 陈文华 牛永杰 李帅霖 于 2021-09-13 设计创作，主要内容包括：本发明公开了一种砂卵石地质变截面螺杆桩施工工艺,其特征在于,包括以下步骤：步骤一：测量放线；步骤二：移动螺杆钻机就位钻螺杆桩孔；步骤三：灌装及拔管；步骤四：灌注混凝土结束后,移开钻杆并沉放钢筋笼；有益效果在于：采用变截面的构造形状,其主要技术特征表现为桩的“上部为直柱型,下部为螺丝型”,在卵石(砂)地质中满足桩身附加应力的分布规律和刚度变化的同时,调整了卵石(砂)地质层与桩身之间的作用,桩身与岩身(卵石等)产生胶结效应,形成胶结状共同体,增大了桩侧摩阻力和端阻力。此外,桩体下部螺牙对桩周和桩端土体产生斜下挤土效应。(The invention discloses a sand-pebble geological variable cross-section screw pile construction process which is characterized by comprising the following steps of: the method comprises the following steps: measuring and paying off; step two: moving a screw drill to drill a screw pile hole in place; step three: filling and drawing a pipe; step four: after the concrete pouring is finished, the drill rod is removed and the reinforcement cage is sunk; has the advantages that: the pile adopts a variable cross-section structural shape, and is mainly technically characterized in that the upper part of the pile is in a straight column shape, the lower part of the pile is in a screw shape, the action between a geological layer of pebbles (sand) and the pile body is adjusted while the distribution rule and the rigidity change of the additional stress of the pile body are met in the pebble (sand) geology, the pile body and a rock body (pebbles and the like) generate a cementing effect to form a cementing community, and the side frictional resistance and the end resistance of the pile are increased. In addition, the lower screw thread of the pile body generates an inclined soil squeezing effect on soil around the pile and at the pile end.)

1. A sand and pebble geological variable cross-section screw pile construction process is characterized by comprising the following steps:

the method comprises the following steps: measuring and setting out, determining a pile position, and guiding holes in a pebble layer;

step two: moving the screw drill in place; the drilling is started, a drill bit valve is closed, the drilling machine is started, and the drilling speed is slow firstly and then fast; in the pore-forming process, when the drill rod descends by one pitch, the drill rod rotates for more than two weeks to drill to the designed depth of the straight line section of the screw pile to form a cylindrical section of the screw pile; then, when the drill rod descends by one pitch, the drill rod rotates by one circle and drills to the designed depth of the screw pile thread section to form a screw pile thread end;

step three: filling and drawing a pipe; after the hole is formed to reach the designed elevation, stopping drilling, continuously and uninterruptedly pumping concrete into the pile hole, and after the drill rod core pipe is filled with the concrete, reversely rotating the screw drill to lift the drill rod;

in the process of lifting the drill, the drill rod reversely rotates along the formed soil body thread track, and the rotation revolution and the lifting speed of the drill rod are controlled to keep synchronous and matched; wherein, the drill rod rotates a circle, the drill rod rises a pitch, and the pipe drawing speed is controlled at 3m/min at a constant speed; meanwhile, high-pressure fine stone concrete is pumped to quickly fill a threaded section space generated by synchronous rotation and lifting of the drill rod;

when the drill rod is lifted to the designed height of the top surface of the threaded section, the drill rod rotates forwards again or is directly lifted to generate a space with a cylinder, and the drill bit pumps high-pressure concrete for pouring to form the cylindrical section of the pile body until the designed elevation of the pile top;

step four: after the concrete pouring is finished, the drill rod is removed and the reinforcement cage is sunk;

the sleeve is placed into the pile hole, the crane is inching to put down the button to put down the reinforcement cage after the reinforcement cage is aligned with the pile position, then the vibrator is adopted to vibrate the lower cage, the lower cage is slowly put in the process of putting down the reinforcement cage, the verticality and the thickness of the protective layer of the reinforcement cage are guaranteed, and the reinforcement cage is conveyed to the designed elevation.

2. The sand and pebble geological variable cross-section screw pile construction process according to claim 1, which is characterized in that: in the second step, after the drilling machine is in place, the position of the drill rod is adjusted to be aligned with the position of the marker post, and the verticality deviation is not more than 1.0%;

the adjustment of the position of the drill rod is carried out in a mode of combining external adjustment and internal adjustment of the pile machine, wherein the external adjustment is based on four vertical mark rods in four directions around the pile machine for correcting the comparison position, and the internal adjustment of the drilling machine is based on the adjustment of the straightness index displayed by a straightness display in a cab of the pile machine.

3. The sand and pebble geological variable cross-section screw pile construction process according to claim 1, which is characterized in that: and in the third step, the height of the top of the construction pile is higher than the designed elevation by more than 70cm, and after the construction pile is poured and formed, a pile head is covered by wet clay to form a protective layer.

4. The sand and pebble geological variable cross-section screw pile construction process according to claim 1, which is characterized in that: and in the third step, after the thread section of the drill rod completely enters the cylindrical section of the pile body, increasing the pressure of pumping concrete.

5. The sand and pebble geological variable cross-section screw pile construction process according to claim 1, which is characterized in that: and in the fourth step, when the reinforcement cage is lowered, the center distance between the drill rod and the pile body is not less than 2 m.

6. The sand and pebble geological variable cross-section screw pile construction process according to claim 1, which is characterized in that: the concrete is commercial concrete, and the slump is 160 +/-20 mm.

7. The sand and pebble geological variable cross-section screw pile construction process according to claim 1, which is characterized in that: the steel reinforcement cage is characterized in that the distance between main reinforcements of the steel reinforcement cage is +/-10 mm, the distance between stirrups or spiral reinforcements is +/-20 mm, the diameter of the steel reinforcement cage is +/-10 mm, and the length of the steel reinforcement cage is +/-100 mm.

8. The sand and pebble geological variable cross-section screw pile construction process according to claim 1, which is characterized in that: and in the third step, the drill bit is lifted and kept at a constant speed, and the lifting speed is not more than the concrete pouring speed.

9. The sand and pebble geological variable cross-section screw pile construction process according to claim 1, which is characterized in that: and in the fourth step, before the reinforcement cage is put down, the piled soil and other powdery sundries around the pile opening are removed.

Technical Field

The invention relates to the field of building construction, in particular to a sand-pebble geological variable-section screw pile construction process.

Background

When cast-in-place pile construction is carried out under the sandy gravel geological condition, particularly when the content of pebbles is large (more than 70 percent), the particle size of the pebbles is large (more than 100 mm) and the layer thickness of a pebble layer is large, a drill rod is easy to be influenced to shift in the hole forming process, so that hole forming shift is caused, and the hole forming quality is influenced; meanwhile, after the traditional cast-in-place pile is formed, the bearing capacity of the pile body is reduced due to the fact that friction between the pile body and pebbles is small, and particularly in an area with a high underground water level, the bearing capacity of the pile body is reduced obviously. Therefore, the applicant provides a hole forming construction process with good pile forming effect and high performance.

Disclosure of Invention

The invention aims to solve the problems and provide a construction process of a sandy gravel geological variable-section screw pile, and a preferable technical scheme in the technical schemes provided by the invention comprises the following steps: the screw pile mode is adopted for pore-forming construction, so that the pore-forming and pile-forming effects under sandy gravel geological conditions can be improved, the pile-forming construction efficiency is improved, the bearing performance of a pile body is improved, and the like, and the technical effects are explained in detail below.

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

the invention provides a sand-pebble geological variable cross-section screw pile construction process which is characterized by comprising the following steps of:

the method comprises the following steps: measuring and setting out, determining a pile position, and guiding holes in a pebble layer;

step two: moving the screw drill in place; the drilling is started, a drill bit valve is closed, the drilling machine is started, and the drilling speed is slow firstly and then fast; in the pore-forming process, when the drill rod descends by one pitch, the drill rod rotates for more than two weeks to drill to the designed depth of the straight line section of the screw pile to form a cylindrical section of the screw pile; then, when the drill rod descends by one pitch, the drill rod rotates by one circle and drills to the designed depth of the screw pile thread section to form a screw pile thread end;

step three: filling and drawing a pipe; after the hole is formed to reach the designed elevation, stopping drilling, continuously and uninterruptedly pumping concrete into the pile hole, and after the drill rod core pipe is filled with the concrete, reversely rotating the screw drill to lift the drill rod;

in the process of lifting the drill, the drill rod reversely rotates along the formed soil body thread track, and the rotation revolution and the lifting speed of the drill rod are controlled to keep synchronous and matched; wherein, the drill rod rotates a circle, the drill rod rises a pitch, and the pipe drawing speed is controlled at 3m/min at a constant speed; meanwhile, high-pressure fine stone concrete is pumped to quickly fill a threaded section space generated by synchronous rotation and lifting of the drill rod;

when the drill rod is lifted to the designed height of the top surface of the threaded section, the drill rod rotates forwards again or is directly lifted to generate a space with a cylinder, and the drill bit pumps high-pressure concrete for pouring to form the cylindrical section of the pile body until the designed elevation of the pile top;

step four: after the concrete pouring is finished, the drill rod is removed and the reinforcement cage is sunk;

the sleeve is placed into the pile hole, the crane is inching to put down the button to put down the reinforcement cage after the reinforcement cage is aligned with the pile position, then the vibrator is adopted to vibrate the lower cage, the lower cage is slowly put in the process of putting down the reinforcement cage, the verticality and the thickness of the protective layer of the reinforcement cage are guaranteed, and the reinforcement cage is conveyed to the designed elevation.

Preferably, in the second step, after the drilling machine is in place, the position of the drill rod is adjusted to be aligned with the position of the marker post, and the verticality deviation is not more than 1.0%;

the adjustment of the position of the drill rod is carried out in a mode of combining external adjustment and internal adjustment of the pile machine, wherein the external adjustment is based on four vertical mark rods in four directions around the pile machine for correcting the comparison position, and the internal adjustment of the drilling machine is based on the adjustment of the straightness index displayed by a straightness display in a cab of the pile machine.

Preferably, in the third step, the height of the top of the construction pile is higher than the designed height by more than 70cm, and after the pile is poured and formed, the pile head is covered by wet clay to form a protective layer.

Preferably, in the third step, after the threaded section of the drill rod completely enters the cylindrical section of the pile body, the pressure of the pumped concrete is increased.

Preferably, in the fourth step, when the reinforcement cage is lowered, the center distance between the drill rod and the pile body is not less than 2 m.

Preferably, the concrete is commercial concrete, and the slump is 160 +/-20 mm.

Preferably, the spacing between the main reinforcements of the reinforcement cage is +/-10 mm, the spacing between the stirrups or the spiral reinforcements is +/-20 mm, the diameter of the reinforcement cage is +/-10 mm, and the length of the reinforcement cage is +/-100 mm.

Preferably, in the third step, the drill bit is lifted to be kept at a constant speed, and the lifting speed is not greater than the concrete pouring speed.

Preferably, in the fourth step, before the reinforcement cage is lowered, the piled soil and other powdery impurities around the pile mouth are removed.

In conclusion, the beneficial effects of the invention are as follows: the pile adopts a variable cross-section structural shape, and is mainly technically characterized in that the upper part of the pile is in a straight column shape, the lower part of the pile is in a screw shape, the action between a geological layer of pebbles (sand) and the pile body is adjusted while the distribution rule and the rigidity change of the additional stress of the pile body are met in the pebble (sand) geology, the pile body and a rock body (pebbles and the like) generate a cementing effect to form a cementing community, and the side frictional resistance and the end resistance of the pile are increased. In addition, the lower screw thread of the pile body generates an inclined soil squeezing effect on soil around the pile and at the pile end.

Compared with the traditional drilling construction, the variable cross-section screw pile is adopted for hole forming construction, and compared with the traditional drilling construction, the variable cross-section screw pile has no noise, no protection wall slurry pollution and no construction precipitation in the hole forming process, and can effectively accelerate the construction speed and reduce the environmental pollution;

after the hole is formed and the pile is poured, a cementing-shaped community is formed through a cementing effect formed between the threaded section of the pile body and the pebble geological layer, so that the side frictional resistance and the end resistance of the pile are greatly increased, the weighing performance of the pile body is improved, compared with the traditional cast-in-place pile, the cast-in-place pile uses less concrete, and the use cost of reinforcing steel bars and concrete is reduced;

the process is used under the sandy gravel geological condition with higher underground water level, the defects that the traditional cast-in-place pile has serious hole collapse under the geological condition, the underwater pouring quality is difficult to control and the like can be effectively overcome, and the pile forming quality is improved.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.

FIG. 1 is a schematic diagram of the displacement of the peripile soil body of the present invention;

FIG. 2 is a schematic view of the pile end soil displacement of the present invention;

fig. 3 is a simulation effect diagram of the pile body stress bubble of the invention.

Detailed Description

In order to further clarify the objects, technical solutions and advantages of the present invention, the technical solutions of the present invention will be described in detail below. It is to be understood that the described embodiments are merely exemplary of the invention, and not restrictive of the full scope of the invention. All other embodiments, which can be derived by a person skilled in the art from the examples given herein without any inventive step, are within the scope of the present invention.

The invention provides a sand-gravel geological variable-section screw pile construction process which is characterized by comprising the following steps of:

the method comprises the following steps: measuring and paying off, determining a pile position, and arranging a marker post at the pile position; and the hole is led in the pebble layer, and the displacement of the pile body can be avoided by the hole.

Step two: after the movable screw drill is in place, the position of a drill rod is adjusted to be aligned with the position of a marker post, and the verticality deviation is not more than 1.0%; the adjustment of the position of the drill rod is carried out in a mode of combining external adjustment and internal adjustment of the pile machine, wherein the external adjustment is based on four vertical mark rods in four directions around the pile machine for correcting the comparison position, and the internal adjustment of the drilling machine is based on the adjustment of the straightness index displayed by a straightness display in a cab of the pile machine.

And (3) initially drilling, closing a drill bit valve, starting the drilling machine, and slowing down and then speeding up the drilling speed, so that the shaking of the drill rod is reduced, and the deviation of the drilled hole is easy to check so as to correct in time. In the pore-forming process, when the drill rod descends by one pitch, the drill rod rotates for more than two weeks to drill to the designed depth of the straight line section of the screw pile to form a cylindrical section of the screw pile; then, when the drill rod descends by one pitch, the drill rod rotates by one circle and drills to the designed depth of the screw pile thread section to form a screw pile thread end; in the pore-forming process, when the drill rod shakes or is difficult to drill, the drilling speed is slowed down, and the drill hole deflection and displacement are avoided, even the drill rod and the drilling tool are damaged. In the drilling process, the pile machine automatic control system strictly controls the descending speed and the rotating speed of the drill rod, so that the drill rod and the drill rod are matched.

Step three: filling and drawing a pipe; after the hole is formed to reach the designed elevation, stopping drilling, continuously and uninterruptedly pumping concrete into the pile hole, and after the drill rod core pipe is filled with the concrete, reversely rotating the screw drill to lift the drill rod;

in the process of lifting the drill, the drill rod reversely rotates along the formed soil body thread track, and the rotation revolution and the lifting speed of the drill rod are controlled to keep synchronous and matched; wherein, the drill rod rotates a circle, the drill rod rises a pitch, and the pipe drawing speed is controlled at 3m/min at a constant speed; meanwhile, high-pressure fine stone concrete is pumped to quickly fill a threaded section space generated by synchronous rotation and lifting of the drill rod;

when the drill rod is lifted to the designed height of the top surface of the threaded section, the drill rod rotates forwards again or is directly lifted to generate a space with a cylinder, and the drill bit pumps high-pressure concrete for pouring to form the cylindrical section of the pile body until the designed elevation of the pile top; the height of the top of the construction pile is higher than the designed height by more than 70cm, and after the construction pile is poured and formed, a pile head is covered by wet clay to form a protective layer. The pile-forming process needs to be continuously carried out, and the machine can not be continuously poured due to other reasons in the construction process, so that the machine needs to be stopped by avoiding saturated sandy soil and silt layer.

Step four: after the concrete pouring is finished, the drill rod is removed and the reinforcement cage is sunk; before the steel reinforcement cage is put down, soil and laitance on the surface of a pile opening are removed, if the pile hole is filled with soil, the soil is removed, the steel reinforcement cage is cleaned, and the soil is prevented from being fed into the pile body; when the reinforcement cage is carried and hoisted, the framework of the reinforcement cage is prevented from deforming. The steel reinforcement cage is characterized in that the distance between main reinforcements of the steel reinforcement cage is +/-10 mm, the distance between stirrups or spiral reinforcements is +/-20 mm, the diameter of the steel reinforcement cage is +/-10 mm, and the length of the steel reinforcement cage is +/-100 mm.

The sleeve is placed into the pile hole, the crane is inching to put down the button to put down the reinforcement cage after the reinforcement cage is aligned with the pile position, then the vibrator is adopted to vibrate the lower cage, the lower cage is slowly put in the process of putting down the reinforcement cage, the verticality and the thickness of the protective layer of the reinforcement cage are guaranteed, and the reinforcement cage is conveyed to the designed elevation.

In a preferred embodiment of the present invention, in step three, after the threaded section of the drill rod completely enters the cylindrical section of the pile body, the pressure of the pumped concrete is increased.

In the fourth step, when the reinforcement cage is lowered, the center distance between the drill rod and the pile body is not less than 2m, so that personal injury caused by falling soil blocks and stones is prevented;

and in the third step, the drill bit is lifted and kept at a constant speed, and the lifting speed is not more than the concrete pouring speed.

In the construction process, the concrete is commercial concrete, the slump is 160 +/-20 mm, the slump is as low as possible, and the loss of the slump of the concrete is reserved according to the conditions of transport distance, temperature and the like during transportation.

The pile adopts a variable cross-section structural shape, and is mainly technically characterized in that the upper part of the pile is in a straight column shape, the lower part of the pile is in a screw shape, the action between the geological layer of pebbles (sand) and the pile body is adjusted while the distribution rule and the rigidity change of the additional stress of the pile body are met in the pebble (sand) geology, the screw rod pile forming of the pebble layer fully develops and improves the side frictional resistance of the soil body, the stress sharing ratio is improved, and the pile side and the pile end form a complete large stress bubble (refer to fig. 3). The pile body and the rock body (pebbles and the like) generate a cementing effect to form a cementing community, so that the side frictional resistance and the end resistance of the pile are increased. In addition, the lower screw threads of the pile body generate an inclined downward soil squeezing effect on soil around the pile and at the pile end (refer to fig. 1 and 2).

Compared with the traditional drilling construction, the variable cross-section screw pile is adopted for hole forming construction, and compared with the traditional drilling construction, the variable cross-section screw pile has no noise, no protection wall slurry pollution and no construction precipitation in the hole forming process, and can effectively accelerate the construction speed and reduce the environmental pollution; after the hole is formed and the pile is poured, a cementing-shaped community is formed through a cementing effect formed between the threaded section of the pile body and the pebble geological layer, so that the side frictional resistance and the end resistance of the pile are greatly increased, the weighing performance of the pile body is improved, compared with the traditional cast-in-place pile, the cast-in-place pile uses less concrete, and the use cost of reinforcing steel bars and concrete is reduced; the process is used under the sandy gravel geological condition with higher underground water level, the defects that the traditional cast-in-place pile has serious hole collapse under the geological condition, the underwater pouring quality is difficult to control and the like can be effectively overcome, and the pile forming quality is improved. Meanwhile, the technical scheme of the application has the advantages of simple process, strong applicability, no need of special and complex process, and high construction safety and economical efficiency.

The pile-forming quality control indexes are as follows:

the pile diameter deviation is less than or equal to 20;

the pile position deviation is less than or equal to 70;

the verticality deviation is less than or equal to 1 percent;

the thickness of the sediment at the bottom of the hole is less than or equal to 100;

the filling coefficient of the concrete is not less than 1.2.

After pile forming, quality detection is needed, and the method specifically comprises the steps of detecting the compressive bearing capacity of a single pile through a single-pile vertical compressive static load test and detecting the integrity of a pile body concrete structure through a low-strain reflection wave method, wherein a slow-speed load maintaining method is adopted for detecting the compressive bearing capacity of the single pile through the single-pile vertical compressive static load test, and a counter-force device adopts a ballast platform mode; and detecting the integrity of the pile body concrete structure by using a low-strain reflection wave method, determining the defect degree of the pile body and the position of the pile body by using a low-strain reflection wave, and judging the integrity type of the pile body.

The control key points of pile forming quality are as follows:

1. the slump of the concrete is 160 +/-20 mm, the slump is as low as possible, commercial concrete is adopted, and the loss of the slump of the concrete is reserved according to the conditions of transport distance, temperature and the like during transportation. Sampling concrete test blocks, wherein the concrete test blocks are grouped into one group (3 blocks in all) per class;

2. manufacturing tolerance deviation of a reinforcement cage: the main reinforcement spacing is +/-10 mm, the stirrup spacing or the spiral reinforcement spacing is +/-20 mm, the diameter of a reinforcement cage is +/-10 mm, and the length of the reinforcement cage is +/-100 mm;

3. the drilling depth of the drilling machine is not less than the design depth of the pile length, and the control current is not less than 120A;

4. the verticality of a drill rod of the drilling machine is less than or equal to 1 percent, and the length of a single-side suspension wire is not less than 10m by adopting the technical measure of the double-side suspension wire of a tower frame of the drilling machine. The allowable deviation of the pile diameter is-20 to +50 mm.

The measures for ensuring pile forming quality comprise:

1. establishing quality management mechanisms, systems and measures on a construction site, establishing a perfect quality assurance system, and standardizing a quality inspection flow;

2. after the concrete reaches a construction site, checking the slump, wherein the allowable deviation between the actually measured concrete slump and the required concrete slump is +/-20 mm;

3. the compactness of pile body concrete must be ensured in the concrete field pouring process, the pile section size is ensured, the drill bit lifting should be kept at a constant speed, the lifting speed is not more than the concrete pouring speed, and the occurrence of shrinkage and pile breakage is prevented.

The above description is only for the specific embodiments of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present invention, and all the changes or substitutions should be covered within the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the appended claims.