CN212052725U - Karst cave area stake construction structures - Google Patents

Abstract

The utility model provides a karst cave district stake construction structures for punching bored concrete pile construction in the stratum is equipped with the karst cave in this stratum. The pile construction structure comprises a platform, a steel pile casing, a pile hole, a mud stone retaining wall, a pile body and an inner casing. The setting platform is positioned in the karst cave and used for supporting the pile body; the steel casing is buried in the stratum and is higher than the surface of the stratum by a certain height; the steel casing and the karst cave are communicated with each other through the pile hole, and the mud stone retaining wall is arranged in the karst cave area and the wall of the pile hole and used for sealing and seepage prevention; the pile body runs through the soil layer from top to bottom, and the bottom of the pile body is connected with the setting platform. The inner sheath is arranged on the outer ring of the pile body and used for blocking the flow of plastic filling materials or water in the karst cave. The utility model discloses a karst cave district stake construction simple structure, the strong operability, the pore-forming quality is reliable, has the commonality to karst cave district pile foundation construction, convenient to popularize and use.

Description

Karst cave area stake construction structures

Technical Field

The utility model relates to a construction technical field, in particular to solution cavity district stake construction structures.

Background

Pile foundation construction refers to the construction process of building foundation, and with the development of underground engineering, the conditions of foundation pit construction in complex geological areas such as karst are gradually increased. Karst caves in karst areas are usually buried at different depths underground, and when a hole is drilled downwards, the karst caves and karst fractures are distributed at different positions below the designed position of the drilled hole, some parts are overlapped, and some parts are close to the hole wall.

The existing construction of punching and pouring piles is to use punching hammer to crush the soil (rock) layer and to compact the soil (rock) layer on the hole wall, so that a container formed on the hole wall is used for pouring concrete to form a pile; the karst cave is a karst stratum structure of an underground cavity formed due to geological action, has complexity and invisibility, and is difficult to construct by punching and filling piles in a karst cave area; and the existing pile construction structure has poor sealing performance, and mud is easy to run off in the construction process, so that the construction cost is greatly increased. Therefore, it is necessary to provide a construction structure for piles in a karst cave area to solve the above technical problems.

SUMMERY OF THE UTILITY MODEL

The utility model provides a karst cave area pile construction structure, which fills clay and rubble at the karst cave part and uses a punching hammer to impact the filler to fill and compact the karst cave or to cover a protective cylinder at the karst cave part, so as to solve the problems that the karst cave area pile construction structure in the prior art is more insufficient in structural design, the karst cave area is subjected to punching cast-in-place pile construction, and the construction difficulty is large; the existing pile construction structure has poor sealing performance and the mud is easy to run off in the construction process.

In order to solve the technical problem, the utility model adopts the technical scheme that: a karst cave area pile construction structure is used for punching and pouring pile construction in a stratum, a karst cave is arranged in the stratum, and the pile construction structure comprises a pile body and a pile body, wherein the pile body is provided with a plurality of holes;

the setting platform is positioned in the karst cave and used for supporting the pile body;

the steel casing is positioned above the karst cave, is embedded in the stratum and is higher than the surface of the stratum by a certain height;

the pile hole is positioned above the setting platform and is used for communicating the steel casing with the karst cave, and the pile hole is concentric with the steel casing and has a diameter smaller than that of the steel casing;

the mud-rock protecting wall is arranged on the inner wall of the karst cave and the wall of the pile hole and is used for sealing and seepage prevention; and the number of the first and second groups,

the pile body, the soil layer down runs through from last to the pile body, just pile body bottom with set up the platform and connect. The embodiment treats the karst cave by filling clay and rubble, and has the advantages of simple construction, strong operability and good pile foundation pore-forming quality.

The utility model discloses in, pile construction structure still protects a section of thick bamboo in the cover, the cover is protected a section of thick bamboo cover and is established pile body outer lane is used for blocking the flow of plastic filling or water in the solution cavity. The flow of plastic filling or water in the karst cave is blocked by the inner casing protection cylinder, so that the pile is convenient to form. Is favorable for improving the quality of the pile foundation.

Furthermore, the inner protective sleeve comprises at least one section of short protective sleeve, and a reinforcing steel strip is arranged at the joint of the adjacent short protective sleeves. The inner protective sleeve is formed by connecting a plurality of sections of short protective sleeves, so that the construction is convenient; the stability of the welding position of the adjacent short protection cylinder is improved by the reinforced steel belt.

The utility model discloses in, the mud stone dado includes clay, slabstone and mud, clay with the slabstone layering is backfilled, clay with the slabstone passes through mud is immersed to it is fixed as an organic whole. The karst cave is filled with clay and rubble and impacted by impact hammer, or the karst cave is sleeved with a protective sleeve to make the hole wall tight and prevent collapse, so that a container without slurry leakage is formed and slurry is prevented from loss.

The utility model discloses in, the stake body includes steel reinforcement cage and concrete, the steel reinforcement cage sets up protect in the cover a section of thick bamboo, the concrete fills extremely through the pipe protect in the cover a section of thick bamboo. The structure is simple, and the pouring pile forming is convenient.

Furthermore, sheet iron is wrapped around the position, located in the karst cave area, of the reinforcement cage, and is used for preventing loss of the poured concrete. The bottom end of the steel bar cage is wrapped with the sheet iron, so that the loss of the poured concrete is prevented, and the waste of materials is avoided.

In the utility model, the height of the karst cave is less than 5m, and the diameter of the inner ring of the inner casing is 0.20-0.22 m larger than the diameter of the pile body; the inner diameter of the steel casing is 0.24-0.27 m larger than that of the inner casing.

The diameter of the plate stone is not more than 30cm, and not more than 1/3 of the diameter of the pile body.

The bottom end of the steel casing is provided with a thickening layer for preventing the steel casing from curling, and the thickness of the wall of the steel casing is between 8mm and 10 mm.

The top of the steel casing is provided with a slurry overflow port which is communicated with the slurry pool. The grout overflow port avoids the waste of materials caused by excessive pouring concrete and avoids influencing the forming of the pile.

The utility model discloses compare in prior art, its beneficial effect is: the utility model discloses a solution cavity district stake construction structures can handle rapidly to the solution cavity that appears in the pile foundation construction, simple structure, and the operability is strong, and the pore-forming quality is reliable, has the commonality to the construction of solution cavity district pile foundation, convenient to popularize and use.

The utility model fills clay and rubble in the karst cave part, and then uses the impact hammer to impact the filler to fill and compact the karst cave or the sleeve in the karst cave part to ensure the hole wall to be tight and not collapse the hole, thereby forming a slurry-tight container, ensuring that the slurry in the hole is not lost, and improving the sealing performance of the structure in the pile construction process; the mud in the hole is guaranteed not to run off, the mud circularly flows in the hole, mud residues in the hole are carried outside the hole, the punching hole achieves the effect of footage hole forming, the construction efficiency is greatly improved, and the cost of pile construction is greatly reduced.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required to be used in the embodiments are briefly introduced below, and the drawings in the following description are only corresponding drawings of some embodiments of the present invention.

Fig. 1 is a schematic overall structure diagram of a preferred embodiment of the karst cave area pile construction structure of the present invention.

Fig. 2 is a steel casing structure diagram of the preferred embodiment of the karst cave area pile construction structure of the present invention.

Fig. 3 is a structural view of an inner casing of a preferred embodiment of the karst cave area pile construction structure of the present invention.

Reference numerals: the karst cave is 11, the setting platform 12, the steel pile casing 13, the grout overflow port 132, the mud stone retaining wall 14, the inner casing 15, the short pile casing 151, the reinforcing steel belt 152, the pile body 16, the steel reinforcement cage 161, the concrete 162, the covering layer 171, the permeable layer 172 and the impermeable layer 173.

Detailed Description

The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments in the present invention, all other embodiments obtained by the skilled in the art without creative work belong to the protection scope of the present invention.

In the drawings, elements having similar structures are denoted by the same reference numerals.

The terms "first," "second," and the like in the terms of the present invention are used for descriptive purposes only and are not to be construed as indicating or implying relative importance, nor should they be construed as limiting in any way.

Referring to fig. 1 and 3, fig. 1 is a schematic diagram of an overall structure of a preferred embodiment of a karst cave area pile construction structure of the present invention, and fig. 3 is a structural diagram of an inner casing of a preferred embodiment of a karst cave area pile construction structure of the present invention.

Following does the utility model provides a pair of solution cavity district stake construction structures of above technical problem can be solved, this stake construction structures is arranged in the stratum towards the construction of hole bored concrete pile, is equipped with solution cavity 11 in this stratum. The pile construction structure in this embodiment includes a setting platform 12, a steel casing 13, a pile hole, a mudstone retaining wall 14, and a pile body 16. Wherein, the setting platform 12 is positioned in the karst cave 11 and is used for supporting the pile body; the steel casing 13 is positioned above the karst cave 11, and the steel casing 13 is buried in the stratum and is higher than the surface of the stratum by a certain height; the pile hole is positioned above the setting platform 12 and communicates the steel casing 13 with the karst cave 11, and the pile hole is concentric with the steel casing 13 and has a diameter smaller than that of the steel casing 13. The mud-stone retaining wall 14 is arranged in the karst cave area and the wall of the pile hole and is used for sealing and seepage prevention; the pile body 16 penetrates through the soil layer from top to bottom, and the bottom end of the pile body 16 is connected with the setting platform 12.

Further, the pile construction structure in this embodiment further includes an inner casing 15, and the inner casing 15 is sleeved on an outer ring of the pile body 16 and is used for blocking the flow of the plastic filler or water in the karst cave 11, thereby facilitating the formation of the pile foundation.

Referring to fig. 3, fig. 3 is a structural diagram of an inner casing 15 according to a preferred embodiment of the construction structure of piles in a karst cave area of the present invention.

The inner casing 15 in this embodiment includes at least one short casing 151, and a reinforcing steel strip 152 is disposed between the multiple short casings 151 and at the joint of the adjacent short casings 151. The inner casing protection tube 15 in the embodiment is formed by welding a plurality of sections of short protection tubes 151, so that the construction is convenient; and a reinforcing steel strip 152 is welded at the welding position of the two sections of short protecting cylinders 151, so that the stability of the whole structure of the inner protecting cylinder 15 is improved. The height of the karst cave 11 in the embodiment is less than 5 m; the diameter of the inner ring of the inner casing 15 is 0.20-0.22 m larger than that of the pile body 16; the inner diameter of the steel casing 13 is 0.24-0.27 m larger than that of the inner casing 15.

In the embodiment, please refer to fig. 1 for the mud-stone retaining wall 14; the mudstone guard wall 14 in this embodiment comprises clay, slate, and mud, wherein the clay is backfilled with slate in layers, and the clay and slate are secured together by the immersion of the mud. The karst cave 11 is filled with clay and rubble, and then the impact hammer is used for impacting the filler to fill and compact the karst cave 11 or the sleeve 15 is sleeved at the position of the karst cave 11 to ensure that the hole wall is tight and does not collapse, so that a container which does not leak slurry (namely the arrangement platform 12 in the embodiment) is formed, and the slurry is ensured not to run off. The diameter of the platelets in this embodiment is no greater than 30cm and no greater than 1/3 of the diameter of the pile body 16.

The pile body 16 in this embodiment is shown in fig. 3; the pile body 16 in this embodiment includes a reinforcement cage 161 and concrete 162, and when the pile is constructed, the reinforcement cage 161 is vertically disposed in the inner casing 15, and the concrete 162 is poured into the inner casing 15 through a conduit. The pile body 16 has a simple structure and is convenient for pouring and forming piles.

The bottom end of the reinforcement cage 161 in the embodiment is wrapped by the sheet iron, so that the loss of the poured concrete 162 is prevented, and the waste of materials is avoided.

The steel casing 13 in this embodiment is shown in fig. 1 and 2; the bottom end of the steel casing 13 in the embodiment is provided with a thickening layer for placing the steel casing 13 to curl; in addition, the thickness of the cylinder wall of the steel casing 13 is between 8mm and 10 mm. The top end of the steel casing 13 is provided with a grout outlet 131, and the grout outlet 131 is communicated with a mud pit of a construction site, so that the waste of materials caused by excessive pouring concrete 162 is avoided, and the influence on pile forming is avoided.

The utility model discloses a solution cavity district stake construction structures's theory of operation: the punching bored concrete pile is characterized in that a soil (rock) layer is crushed by punching hammer and is compacted by the soil (rock) layer on the hole wall, so that the hole wall forms a container which is compact and not leak, the karst cave 11 is an underground cavity karst stratum structure formed under the geological action, the complexity and invisibility are realized, the punching bored concrete pile construction is carried out in a karst cave area, the construction difficulty is high, and the construction quality of a pile foundation can be ensured only by adopting corresponding technical measures aiming at the foundation of the karst cave 11.

The following embodiment shows the construction process of the construction of the hole-punching cast-in-place pile in the karst cave area with the height within 5m, and the technology of filling clay, adding stones and arranging the inner casing 15 in the karst cave 11 is adopted, so that the pile foundation hole forming quality is good.

Firstly, construction preparation.

1. And (4) predicting problems possibly occurring in the construction according to geological survey data, formulating a drilling construction scheme, and performing technical optimization on drilling machine operators. The soil layer in the embodiment of the city sequentially comprises a covering layer 171, a water permeable layer 172 and a water impermeable layer 173 from top to bottom, wherein the covering layer 171 is cohesive soil, sandy soil or miscellaneous filling soil; impermeable bed 173 is a rock bed.

2. The materials required by the construction of the foot-prepared pile foundation, such as clay, rubble, cement, steel casing 13, steel bars, concrete and other construction materials.

3. The pile machine equipment is checked before the pile machine is in place, the equipment is guaranteed to be normal, and meanwhile, the diameter and the integrity of the hammer head are checked to guarantee that the diameter of a formed hole meets the design and specification requirements.

And secondly, leveling the field.

Before the construction of the pile machine, an excavator is used for leveling an area to be constructed of the pile machine to form a basically flat operation platform so as to prevent the pile machine from sinking and hole positions from inclining.

And thirdly, measuring and paying off.

After the basic leveling of the site is completed, a measurer accurately measures and positions the site according to the pile position coordinates of design drawings, determines the center position of the pile, and buries and lays a protection pile on the longitudinal and transverse center lines of the pile position so as to check the hole position at any time in the construction process.

Fourthly, drilling by piles.

And (3) laying exploration holes on the pile positions according to geological exploration data, and performing pile-to-pile hole exploration by adopting a geological drilling machine to determine the geological condition of each pile hole. The exploration content is approximately the conditions of the burial depth, the size and the geology of the karst cave 11, the type of a filling material in the karst cave 11, the trend of the karst cave 11, an underground water system and the like, so that different construction methods are set for each pile position to ensure the smooth construction of a pile foundation.

And fifthly, embedding the steel casing 13.

1. The steel casing 13 in the embodiment is rolled and welded into a circle by adopting a steel plate with the thickness of 8-10 mm, the inner diameter of the steel casing is 20cm larger than the designed pile diameter, the top surface of the steel casing is 20-30cm higher than the construction ground, a grout outlet 131 is reserved in the top casing, the grout outlet faces a mud circulation pool or a mud pool, the steel casing is buried in a manually-excavated hole, and the periphery of the bottom of the steel casing is filled with clay to be tamped so as to prevent grout leakage.

2. Embedding depth of the steel casing 13: the thickness of the clay is not less than 1.0m in the cohesive soil; the sand and the miscellaneous fill are not less than 1.5m, and the height of the sand and the miscellaneous fill meets the requirement of the height of the slurry surface in the hole.

3. Before the pile driver is in place, a technician rechecks the pile position, the deviation between the center of the top surface of the steel casing 13 and the pile position is not more than 5cm, and the inclination is not more than 1%.

And sixthly, preparing slurry.

And excavating a mud pit, selecting and preparing good slurry-making clay, adding a proper amount of bentonite, sodium carbonate, caustic soda and the like according to needs, and making slurry by rotating a machine, wherein the slurry-making amount is 2-3 times of the volume of the pile concrete 162, and the specific gravity of the mud can be timely adjusted according to geological conditions of different stratums to ensure that all performance indexes of the mud meet the use requirements. The mud concentration of the soil layer and the rock layer is 1.1-1.3, and the sand concentration of the gravel layer is 1.3-1.5.

And seventhly, positioning the pile driver.

The frame is erected, and the hoisting system is adjusted and installed, so that the impact hammer is hoisted and slowly placed into the protective cylinder. The percussion drill is aligned with the center of the protective cylinder, and the deviation is not more than +/-20 mm.

Eighthly, punching and cave 11 treatment.

1. When the hole is opened, a small stroke is used for punching, the hammer is used for impacting closely, and the hole is slowly punched at a low gear at the bottom of the protective cylinder, so that a firm mud skin protective wall is arranged at the bottom of the protective cylinder. If the soil on the outer side of the casing is soft and leaks slurry, the drill bit can be lifted, clay is poured into the hole, the drill bit is lowered to reduce the impact speed, cement is extruded into the hole wall to block the slurry leakage hole, and the drilling is continued after the slurry is stabilized.

2. And (3) increasing the stroke after the punched hole enters the bottom of the steel casing 13 for 2-3 m, wherein the lengthening amount of the main rope is 3-5 cm. Meanwhile, the punching geological inspection and rechecking are enhanced, the working condition of the drilling machine, the surrounding ground surface settlement and the water level change in the casing are closely observed, and the abnormal condition is prevented.

3. According to the geological histogram, when approaching the karst cave 11, frequently observing and frequently checking, and judging whether approaching the stratum of the karst cave 11 or not by the sound of the drill bit impacting the rock stratum and the extracted rock sample. The length of the main rope is controlled to be 1-2 cm when the main rope approaches the karst cave 11, so that drill jamming during rock shell puncture is prevented, and one of methods of filling clay and rubbles and sleeving a casing 15 is selected according to the height of the karst cave 11, the filling condition and the economy to carry out pile hole karst cave 11 layer construction.

1) Clay filling and stone adding method. The full-filled, half-filled and unfilled caverns 11 with a height of 5m and below are produced by a clay-filled and rubble-filled method.

When the holes are punched to the karst cave 11 layer, clay and rubbles (according to the volume ratio of 1: 1) are adopted for layered backfilling, one layer of clay is backfilled one layer of rubbles, when the karst cave 11 is larger, partial cement can be added, one layer of backfilling is carried out, a drill is adopted for impacting once, and the rubbles and the clay are kept compact as far as possible until the top of the karst cave 11 is backfilled to 1-2 m.

After the karst cave 11 is backfilled, slurry with high consistency is injected into the drill hole to enable the drill hole to be naturally immersed into the gaps of the stones, and then the drill bit is adopted to impact the drill hole to enable the clay and the stones to be squeezed into the karst cave 11 to form the mud stone protective wall 14.

If slurry leakage occurs in the mud-rock protecting wall 14 in the karst cave 11, backfilling and impacting are carried out again, wherein the backfilling and the impacting are carried out twice or three times repeatedly until the mud-rock protecting wall 14 is formed and slurry leakage does not occur any more, and the platform 12 is arranged for forming.

2) And (4) sleeving a protective sleeve 15. No filling or plastic filling materials are filled in the holes with the height of 5m or below, and when water leakage is serious or the holes are communicated with a river, construction is carried out by adopting an inner protective sleeve 15 method.

The inner protective sleeve 15 is formed by welding single-section or multi-section short protective sleeves 151, and the length of the single-section protective sleeve is 1.5-2.5 m. The first section of the single-section or multi-section protective barrel is buried manually, after the multi-section protective barrel is punched to a certain depth, the second section of protective barrel is welded, a protective cap is placed on the top of the protective barrel, the protective barrel is impacted into the soil by a drill bit, then the protective barrel is punched, the third section of protective barrel is welded, and the process is circulated until the required depth is reached, so that the flow of plastic filling materials or water in the karst cave 11 is blocked, and punching construction is facilitated.

In the process of sinking the pile casing, the pile casing should sink stably and uniformly, the drill bit must be centered on the top surface of the pile casing, the pile casing is prevented from deflecting due to eccentricity as much as possible, and meanwhile, the verticality of connection of all sections of pile casings is well controlled, and the pile casing is strived to enter the soil vertically. If the tendency of deflection is once corrected, the adverse factors of possible deflection are eliminated in the bud state.

In addition, the inner diameter of the inner casing protection barrel 15 is larger than the pile diameter by 0.2m, and the inner diameter of the steel casing protection barrel 13 is larger than the inner diameter of the inner casing protection barrel by 0.25 m. In order to ensure the rigidity of the inner protective cylinder 15 and prevent compression deformation, the steel protective cylinder 13 is rolled by 8-10 mm steel plates, and the bottom edge foot of the steel protective cylinder 13 is thickened by the steel plates to prevent curling.

Length of the inner sheath tube 15: the length L of the casing protection cylinder is h +3(m), wherein h is the height of the karst cave 11 determined by the geological drilling rig, and if the casing protection cylinder 15 is too long, the casing protection cylinder can sink in a segmented mode and is connected with the opening in a welding mode.

When the inner protection tube is welded, the short protection tubes 151 are welded and connected by adopting a double-sided groove to carry out full welding, and the seam of the two short protection tubes 151 needs to be welded with a 50mm wide reinforcing steel strip 152 (10 mm) at the welding seam in addition to welding so as to ensure the accurate size of the inner protection tube, so that the straightness of the inner protection tube 15 meets the requirement, and the vertical wall of the whole inner protection tube 15 is in a straight line.

The verticality of the inner protective sleeve 15 of the control sleeve. In the falling process, the verticality is controlled by an external special bracket and a clamp of the embedded steel protective cylinder 13 and assisted by a theodolite; the verticality of the inner protective cylinder 15 in the welding process is controlled: and leveling the lower inner pile casing by using a sizing block (adjusted by a crane), detecting by using a leveling ruler to meet the level requirement, preliminarily positioning the upper pile casing in place in the range of an external fixture, aligning the interfaces, measuring the verticality by using a theodolite, leveling the sizing block at the interface part if the verticality exceeds the standard requirement, then spot-welding two short pile casings 151, and after preliminary stabilization, performing full-length welding. After the weld bead is cooled, another short liner 151 is dropped, and the above process is repeated.

And (5) solidifying the blade of the inner protective sleeve 15. When the inner casing 15 passes through the karst cave 11 to the next rock face, the rock face is generally inclined, the periphery of the inner casing can not be in complete contact with the rock face, a large gap can be formed between the inner casing and the rock face, if the inner casing is not solidified, a pile hole and a channel outside the pile can be formed in the rock-entering and rushing-in process, and therefore deviated holes or inclined holes are easily generated when the casing is buried and the casing foot passes, and potential quality hazards are left.

During construction, the method is adopted for processing, block stones and clay are thrown and filled within the range of the blade foot of the inner protective cylinder by utilizing the characteristic that the hole wall is extruded during impact hole forming, the punching is carried out by using a stroke of 2-4m, so that the hole wall is compactly manufactured, the punching is repeated for many times until the hole bottom is flat, and uneven rock surfaces can be punched simultaneously during processing.

In this embodiment, the punching quality is controlled as follows:

when the pile casing is buried, the top of the pile casing is 20-30cm higher than the ground, the general burying depth is 2-4m, and the pile casing penetrates through the water permeable layer 172, so that the smooth operation of punching and concrete pouring is ensured.

When the drilling machine is used for positioning, the deviation between the center of the drill bit and the center of the hole site is not more than 5cm, so that the punching positioning is accurate, the base is stable, and the top is not inclined. The displacement generated in the drilling process should be adjusted in time to avoid the phenomena of hole deviation and inclined holes.

In the punching construction, the plane position and elevation of the pile casing are frequently rechecked to prevent the pile casing from inclining or deviating from the hole and ensure that the deviation between the punching center and the designed pile position is not more than 5 cm.

In the punching process, a hole checking device is often adopted to check the hole diameter and the hole shape, so that shrinkage holes and plum blossom holes are prevented from occurring, and the hole is not bent and inclined. The pile diameter is ensured to meet the design requirement, and the punching inclination is not more than 1%.

When the karst cave 11 is processed: the clay is natural bulk clay without impurities, the diameter of the flaky stone is not more than 30cm and not more than 1/3 of the diameter of the pile, the steel casing 13 is rolled and welded into a circle by a steel plate with the thickness of 8-10 mm, and the inner diameter of the steel casing is more than 20cm of the diameter of the pile.

After the karst cave 11 is processed, slurry supplementing channels around the holes are cut off, whether the slurry surface in the holes still changes or not is observed, and slurry leakage is avoided.

And the ballast is cleaned by adopting a secondary hole cleaning method, and the settled ballast at the bottom of the hole is cleaned before concrete is poured, so that the thickness of the settled ballast at the bottom of the hole is ensured to meet the standard requirement.

4. The rock formation is flushed.

The surface of the rock formation is mostly uneven or inclined, so that the hole is most likely to be deviated when the punched hole just reaches the rock formation. Special care is taken when the punch contacts the formation. Usually, a stone slab with a diameter of 20-30cm is thrown to the bottom of the hole, and the inclined plane and the uneven part of the rock stratum are filled and filled. Then, the rope is tightened, the rope is hammered at low hammer speed, a compact platform is formed, the impact hammer is supported, the force is uniformly applied, and hole deviation is prevented. However, the hammer cannot be raised until the inclined protruding part of the rock stratum is not leveled, the hammer can be hammered to a high degree after the rock stratum is basically leveled, the mud concentration is reduced to about 1.2 after the punching progress is accelerated to be punched into the rock stratum, so that the resistance and the hammer sticking condition are reduced, but the mud concentration cannot be too small, otherwise, the stone slag cannot float upwards, and the slag spreading is difficult.

5. After passing through the rock formation, the punching is continued until the design depth.

Ninth, cleaning and checking.

1. And when the elevation, the aperture, the verticality and the like of the hole bottom meet the design standard requirements and the detection is qualified, cleaning the hole.

2. And (3) cleaning the hole by adopting a slurry pump, pressing slurry into the bottom of the hole at a medium speed through a drill rod, replacing the slurry with a large amount of suspended drilling slag in the hole, and keeping the water level in the hole to avoid hole collapse.

3. And when all indexes of the slurry discharged from the hole meet the standard requirements, the hole cleaning can be stopped, the drilling and acceptance are carried out, and the reinforcing cage 161 can be hung and installed after the acceptance passes.

And tenthly, installing the reinforcement cage 161.

1. The reinforcement cage 161 is manufactured in a reinforcement processing factory, and the reinforcement cage 161 can be processed and manufactured in sections when being long, and is hoisted and lengthened on site in a sectional transportation mode.

2. The reinforcement cage 161 is suspended by a drill stand or a truck crane, and is righted and slowly lowered when entering the orifice, and is strictly prohibited to swing to collide the hole wall.

Eleven, installing a guide pipe.

1. The installation conduit is made of a seamless steel pipe with the diameter of 300mm, each section is 2.0-5.0 m long, 1-2 sections are short pipes with the length of 0.5-1.5 m, and the short pipes are connected through screw threads. Before use, the conduit is subjected to watertight, pressure-bearing and joint tensile tests, so that the conduit is ensured to be watertight.

2. After the guide pipe is installed, a space of 250-400 mm is reserved between the bottom of the guide pipe and the bottom of the hole. The concrete pouring support is made of profile steel and is used for supporting the suspension guide pipe and the suspension reinforcement cage 161, and the concrete funnel is placed at the upper part.

And twelfth, secondary hole cleaning.

Because the bottom of the hole can generate dregs when the reinforcement cage 161 and the guide pipe are placed, secondary hole cleaning is carried out after the reinforcement cage 161 and the guide pipe are in place, the secondary hole cleaning method is the same as the primary hole cleaning method, the secondary hole cleaning is qualified, and then the concrete 162 can be poured.

Thirteen, pouring concrete 162.

The method comprises the following steps of (1) preparing more materials by considering the requirements of reaming and filling the karst cave 11 before pouring, and properly increasing the buried pipe depth (the buried pipe depth is preferably 6-10 m) of the karst cave region during pouring so as to avoid the problem that when concrete is poured, the concrete in a pile hole fills the karst cave 11 due to the fact that the protective wall of the karst cave 11 is collapsed, and the concrete surface is suddenly lowered to expose the concrete surface of a conduit port, so that pile breakage accidents are caused; in addition, in order to reduce the loss of concrete in the pouring process, sheet iron can be wrapped around the position, located in the karst cave area, of the reinforcement cage 161, meanwhile, the monitoring strength in the concrete pouring process is enhanced, and the problem is found and solved in time.

Pouring of the concrete 162 is continuously carried out, stopping pouring strictly midway, when the surface of the concrete 162 rises to the lower end of the reinforcement cage 161, in order to prevent the reinforcement cage 161 from being jacked and lifted by the concrete 162, the pouring speed of the concrete 162 is slowed down as much as possible, the impact force of the concrete 162 after the concrete is discharged from the bottom opening of the guide pipe is reduced, when the guide pipe is lifted, the position is kept in the center, the lifting height is determined according to the embedding depth of the guide pipe, the lifting height of the guide pipe after the lifting is not less than 1m, and the pouring elevation of the pile top is more than the designed elevation by more than 0.5 m.

In this embodiment, the step of controlling the pouring quality of the concrete 162 is as follows:

1. pile foundation concrete 162 is poured by a conduit method, and trial splicing, pressure testing and trial pulling are carried out before the conduit is installed, so that firm connection of the joints is ensured, and slurry leakage is prevented.

2. The guide pipe is placed in the center of the drilled hole, the distance between the lower opening and the bottom of the drilled hole is 25-40 cm, and the depth of the guide pipe embedded into the concrete 162 after the first batch of concrete 162 enters the drilled hole is not less than 1 m.

3. And continuously pouring the concrete 162, wherein the position of the top surface of the concrete 162 in the hole is often measured in the pouring process, and the buried depth of the guide pipe is kept within the range of 1-3 m (the buried pipe depth of the 11 layers of the karst cave is 6-10 m).

4. When the guide pipe is disassembled, the lifting height of the guide pipe is strictly controlled, the buried depth of the guide pipe is kept to be not less than 1m, and the pile breaking accident caused by overhigh lifting of the guide pipe is avoided.

Fourteen, pile foundation detection.

After the pile foundation construction is completed, according to the standard and design requirements, the bearing capacity, pile body integrity and the like of the pile foundation are detected and evaluated within a specified time, and the pile foundation forming quality is judged.

Thus, the construction process of the karst cave area pile construction structure of the preferred embodiment is completed.

In summary, although the present invention has been described with reference to the preferred embodiments, the above-described preferred embodiments are not intended to limit the present invention, and those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention, so that the scope of the present invention shall be determined by the scope of the appended claims.

Claims (10)

1. A karst cave area pile construction structure is used for punching and pouring pile construction in a stratum, and a karst cave is arranged in the stratum;

the setting platform is positioned in the karst cave and used for supporting the pile body;

the steel casing is positioned above the karst cave, is embedded in the stratum and is higher than the surface of the stratum by a certain height;

the pile hole is positioned above the setting platform and is used for communicating the steel casing with the karst cave, and the pile hole is concentric with the steel casing and has a diameter smaller than that of the steel casing;

the mud-rock protecting wall is arranged on the inner wall of the karst cave and the wall of the pile hole and is used for sealing and seepage prevention; and the pile body penetrates through a soil layer from top to bottom, and the bottom end of the pile body is connected with the setting platform.

2. The karst cave area pile construction structure according to claim 1, further comprising a sleeve casing, wherein the sleeve casing is sleeved on the outer ring of the pile body and used for blocking the flow of plastic filling or water in the karst cave.

3. A karst cave area pile construction structure according to claim 2, wherein the inner casing includes at least one short casing, and a reinforcing steel strip is provided adjacent to the junction of the short casings.

4. A karst cave area pile construction structure according to claim 1, wherein the mud-stone retaining wall includes clay, slate, and slurry, the clay and the slate are backfilled layer by layer, and the clay and the slate are immersed by the slurry to be fixed as one body.

5. A karst cave area pile construction structure according to claim 2, wherein the pile body comprises a reinforcement cage and concrete, the reinforcement cage is arranged in the inner casing, and the concrete is poured into the inner casing through a guide pipe.

6. A karst cave area pile construction structure as claimed in claim 5, wherein the reinforcement cage is wrapped with sheet iron around the position of the karst cave area for preventing the loss of the poured concrete.

7. A karst cave region pile construction structure according to claim 2, wherein the height of the karst cave is less than 5m, the diameter of the inner ring of the inner casing is 0.20-0.22 m larger than the diameter of the pile body; the inner diameter of the steel casing is 0.24-0.27 m larger than that of the inner casing.

8. A cavern region pile construction structure as claimed in claim 4, wherein the diameter of the rubble is not more than 30cm and not more than 1/3 of the diameter of the pile body.

9. A karst cave area pile construction structure as claimed in claim 1, wherein a thickening layer is provided at the bottom end of the steel casing for preventing the steel casing from curling, and the thickness of the wall of the steel casing is between 8mm and 10 mm.

10. A karst cave area pile construction structure as claimed in claim 1, wherein the top of the steel casing is provided with a slurry overflow port, and the slurry overflow port is communicated with a slurry pool.

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