CN111305241A - Method for treating quicksand in hole digging of manual hole digging pile through light well point dewatering - Google Patents

Abstract

The invention relates to a method for treating drift sand in manual hole digging pile hole digging by light well point dewatering, which adopts a punching and dewatering device for treating drift sand and is characterized in that a concrete retaining wall at the upper part of a drift sand layer is manufactured; punching holes obliquely outwards along the water surface part of the quicksand layer at the bottom of the retaining wall; assembling and connecting a flexible water collecting pipe, connecting a well point pipe and the flexible water collecting pipe by using a connecting pipe, hoisting and draining a water pump into the bottom of a pile hole by using a small winch equipped for hole digging, connecting the flexible water collecting pipe by using a water suction port of the water pump, and pumping and draining water to enter a sand flowing layer of the hole digging pile for dewatering, digging and concrete supporting; and (4) after the quicksand treatment is finished, digging holes to the designed depth of the pile holes, continuously maintaining precipitation until the pile holes are qualified for inspection, stopping the pump before preparing to lower the reinforcement cage, withdrawing the drainage pump and the drainage pipe in the pile holes, and removing the flexible water collection pipe and the connecting pipe. The invention has high precipitation efficiency and high precipitation speed, is more suitable for simultaneously treating the quicksand by a plurality of pile holes, can generate a group well precipitation effect, accelerates the quicksand treatment speed and improves the construction efficiency.

Description

Method for treating quicksand in hole digging of manual hole digging pile through light well point dewatering

Technical Field

The invention relates to a pile foundation construction method in the field of buildings, in particular to a method for treating quicksand in hole digging of an artificial dug pile by light well point dewatering.

Background

In the construction of infrastructure, such as bridge, high-rise building etc., bored concrete pile is the most extensive pile foundation form, wherein, artifical bored concrete pile has irreplaceable effect under some specific conditions (because drilling equipment can't be under construction because of the place reason, because stratum reason rig construction difficulty is big, because of economic benefits contrast special reason not suitable use rig construction etc.). At present, the types of cast-in-place piles suitable for manual hole digging pile construction are as follows:

the single pile type large diameter cast-in-place pile, such as the foundation of a telecommunication signal transmitting tower, generally adopts a cast-in-place pile with a diameter of about 1.5m and a pile length of about 10m as a tower foundation. Various cast-in-place pile construction fields with complicated underground conditions, such as existing railway line reconstruction projects, various telecommunication lines with difficult accurate position determination exist underground, and the cast-in-place pile construction fields are not suitable for mechanical drilling construction; the existing factory area with narrow places is upgraded and transformed to the pile foundation engineering, various underground pipelines and unknown objects in the factory area are complex, and mechanical drilling is easy to cause accidents. The rock-socketed piles are especially suitable for the case that the cover layer is a loose stratum (such as a fine sand layer) on the shallow rock stratum of the pile hole.

The biggest difficult problem of manual hole digging pile construction is that a quicksand layer appears in the hole digging process, and after the quicksand problem appears, the manual hole digging operation cannot be continued due to safety consideration, so that great construction difficulty and economic loss are caused when mechanical drilling is changed. At present, the following methods are used for successfully treating the condition of quicksand of the manual dug pile:

the Chinese invention patent 201210180435.X discloses a construction method for treating a pile foundation super-thick quicksand layer by using a front-end vibration steel casing, which is characterized in that a front-end vibration sinking steel casing is manufactured in advance, a steel clapboard is welded in the steel casing along the axial direction of the steel casing, and the plane of the steel clapboard is parallel to the axial line of the steel casing; after a drift sand layer is excavated by manually digging holes, installing and vibrating a steel casing in a pile hole; after the steel casing is vibrated and sunk to a mud rock layer below a quicksand layer, the excavation is stopped when the hole is manually excavated to a position 30cm away from the bottom of the steel casing, a circle of single reinforcing steel bar with the length of 100cm is implanted into the rest quicksand layer and the mud rock layer at the lower part of the quicksand layer along the edge of the casing, then the steel bar is continuously excavated downwards to a mud rock layer below the quicksand layer by 30cm, and the steel casing can rapidly and efficiently pass through the quicksand layer without influencing the ground construction site and damaging the stratum structure.

The patent has the following disadvantages:

1. the condition of stratum quicksand needs to be known before manual hole digging pile construction, the hole digging aperture is enlarged during hole digging pile upper portion construction, and the method cannot be used if quicksand is found in the hole digging process.

2. According to the construction method disclosed by the patent, (1) the steel pile casing with the vibrating sinking is manufactured, and the inner diameter of the pile hole after the steel pile casing with the inner diameter larger than the designed pile diameter by more than 6cm and (2) the pile hole with the inner diameter larger than the inner diameter of the designed pile hole after the retaining wall is poured on a non-quicksand layer with the inner diameter larger than the quicksand layer are more than 7cm, the construction can not be carried out at all. The reason is that the wall thickness of the steel casing is not less than 1cm, and the outer diameter of the steel casing is greater than the pile diameter by 8 cm; the construction of the retaining wall of the manual hole digging pile is rough, large errors exist among all sections of the retaining wall, and in order to ensure that the steel retaining cylinder is vertical before vibration, the construction level is that the inner diameter of the retaining wall is 5-10 cm larger than the outer diameter of the steel retaining cylinder.

3. The method is only suitable for partially rock-socketed piles (the bottom of the pile is mudstone), the rock stratum is smooth, and the method cannot be successfully used if the rock stratum at the bottom of the pile is in a ditch shape or the condition of the bottom of the pile is that one part of the rock stratum is rock and the other part of the rock stratum is quicksand.

4. The patent relates to a construction method of an ultra-thick quicksand layer, wherein a steel casing is vibrated and sunk by a vibration hammer, and when the steel casing is vibrated and sunk to a certain depth, the quicksand layer in the steel casing is excavated and removed by adopting a manual hole digging mode; according to the construction process description, when the drift sand in the steel casing is manually excavated and removed, a water head pressure difference is formed between the inside and the outside of the steel casing, and the drift sand outside the steel casing continuously flows into the steel casing from the bottom of the steel casing; along with the increase of the depth of the steel casing into the quicksand layer, the pressure difference between the internal water head and the external water head of the steel casing is synchronously increased, the quicksand amount which flows into the steel casing from the outside of the steel casing in unit time is synchronously increased, and particularly when the steel casing is vibrated and sunk, the quicksand inside and outside the steel casing is in a vibration liquefaction state, so that the outflow sand of the steel casing flows into the steel casing more severely; repeated vibration sinking of the steel casing may cause a great loss of sand flowing outside the steel casing, which may cause the concrete retaining wall of the manual hole digging pile on the upper part of the sand flowing layer to fall downwards, thus causing accidents, and after pile forming, a great amount of sand flowing outside the steel casing forms weak holes, which also affects the foundation outside the pile. Therefore, ultra-thick quicksand treatment seems to be difficult to scale.

5. The technology is not suitable for manual hole digging piles with multiple quicksand layers, and only can treat a layer of quicksand on the upper part of the pile bottom of the quicksand layer.

From the economic perspective, the technology of the patent requires the working procedures of steel casing manufacturing, transportation, loading and unloading, hoisting and installation, vibration and sinking and the like; a large-power supply (or a special motor for a vibration hammer), a crane and the like are required to be arranged on site; the pile diameter needs to be increased by using the technology of the patent, and the concrete increase is also larger; whether the technology is economical or not needs to be analyzed and considered according to different engineering conditions, and the technology is certainly not suitable for the engineering with less manual hole digging piles.

From the technical point of analysis, the technology of the patent needs to enlarge the pile diameter of the manual bored pile, needs to communicate with a designer of the manual bored pile, and obtains the permission of the designer or changes the design.

In addition, a paper, "treatment of quicksand layer construction technology of pile excavation and pile excavation in foundation pit supporting engineering", published in 2009 supplement of the national non-metal mining industry (general 76) introduces a method for treating pile excavation and pile excavation, wherein the construction process flow of quicksand layer excavation is as follows:

when a first throttling sand layer is excavated, the periphery of the original protective wall bottom at the front edge of excavation inclines to the outside of a hole by about 15 degrees, reinforcing steel bars with the length of 1000mm and the diameter of phi 16@100 are firstly driven into the hole, 10-20 kg of straws are prepared, and the straws are bundled into small bundles for later use. When the middle is dug to a certain depth, sand outside the periphery flows into the hole along with underground water, at the moment, the bundled straw is plugged into the outer side of the reinforcing steel bar immediately, and the cantilever soil retaining capacity of the reinforcing steel bar anchored below the sand bed is utilized to temporarily support and block the sand bed and offset the lateral pressure of the hole wall.

Along with the downward excavation of the sand layer in the hole, straws are also stuffed in the outer side of the steel bars from top to bottom, the thickness of the stuffed straws is determined according to the thickness of the sand layer, the goal is to block the outflow of sand, water naturally seeps out, and after the sand layer is excavated to a certain depth (300 plus 500mm), the construction of the retaining wall concrete can be carried out. When the retaining wall concrete is constructed, a 50mm protective layer is reserved along the periphery of the bottom of the retaining wall, the protective layer is inclined to the outside of a hole by about 15 degrees, a reinforcing steel bar with the length of 1000mm phi 16@100 is firstly driven in, and a horizontal stirrup phi 8@200 is bound. After the construction, the concrete is poured by supporting the formwork as in the normal hole pile excavation (the water cement ratio of the concrete in the quicksand layer is reduced by properly increasing the cement consumption so as to improve the strength of the concrete or adding an early strength agent). Note that: each section of the retaining wall must be constructed continuously on the day. After 24h, the next excavation can be carried out.

The excavation and construction method of the second throttling sand layer retaining wall is completely the same as that of the first throttling sand layer retaining wall, except that the reinforcing steel bars for supporting and retaining the drift sand during the first excavation are supported and retained by the anchoring force of inserting the lower ends into the sand layer, and the reinforcing steel bars for supporting and retaining the drift sand during the second excavation are supported and retained by the anchoring force of anchoring the upper ends into the concrete of the previous retaining wall. And in turn, may continue to excavate downward.

The paper introduces that the sand flow layer of the manual dug pile is shallow (about 4.50-6.60 m) and the diameter of the pile is larger and phi 2.0 m. Although quicksand layers were successfully treated by quick shoring, the following problems still remain:

the quicksand processing process is tense, and when the quicksand layer is deeper or the pile diameter is smaller, the quicksand processing time is prolonged, the success rate is reduced, and the safety coefficient is reduced. When the quicksand particles of the quicksand layer are fine and the quicksand is in a state of silt-silt, the quicksand cannot be blocked by binding straws, and water cannot naturally flow out. When the quicksand layer is relatively thick, when the quicksand at the lower part is processed, the pressure difference of the internal and external water heads of the retaining wall is increased, the construction difficulty is increased, the danger is increased, the outflow sand of the retaining wall possibly gushes into the hole in a large amount under the action of the pressure difference, so that the outer cavity of the retaining wall is caused, and the construction accident is easily caused.

Therefore, the use of the method is limited by geological conditions, and the application range is small.

Disclosure of Invention

The invention aims to overcome the defects of technical measures for treating the quicksand layer when the existing manual hole digging pile meets the quicksand layer, and provides a dewatering device and a dewatering method for treating the quicksand when the hole digging pile meets the quicksand layer, wherein the dewatering device is small in size, economical to use and safer to construct.

In order to achieve the purpose, the technical scheme of the invention is as follows:

the utility model provides a method that light-duty well point dewatering handled artifical hole digging pile hole and appears shifting sand, adopts hole digging pile hole digging to handle punching a hole and dewatering device of shifting sand when running into the sandy stratum, its characterized in that:

(1) firstly, a punching and dewatering device for treating the quicksand in the hole digging of the manual hole digging pile by using light well point dewatering. When the hole of the hole digging pile meets a quicksand layer, the safe construction cannot be continued, and the quicksand layer needs to be processed, the downward digging is stopped, and the hole digging operator does well the concrete retaining wall on the upper part of the quicksand layer.

(2) Punching: digging a water collecting pit in the middle of a pile hole, connecting and installing a small submersible pump, a water feeding pipe and a punching steel pipe on the ground, putting the punching steel pipe into the pile hole, and punching the punching steel pipe in an outward inclined manner along the water surface part of the quicksand layer at the bottom of the retaining wall; knowing and mastering the thickness of the quicksand layer through a punching process;

if the hole depth is 1.50m and does not reach the bottom of the sand layer, stopping downwards punching, and determining the hole depth of the first step point to be 1.5 m; (i.e. if no water-proof interlayer is found in the punching process, the punched steel pipe can be lengthened and the hole depth can be increased according to the actual situation;)

If the quicksand layer is only one layer and the thickness is not large, and the lower part is a soil layer, the quicksand layer can be penetrated by about 0.2m when the hole is punched;

if the bottom of the sand layer is a rock stratum, the hole is punched until the rock stratum is not moved. Inserting well point pipes and filter pipes on the ground, and putting washed sand (bagged) into the pile holes;

after the hole is punched, keeping the hole depth after the hole depth is about 1.5m, after the punching water is clear, putting a long well point pipe about 1.5m into the hole, stopping punching, and filling washing sand around the well point pipe in the hole, wherein the pipe head is about 0.1m higher than the water surface; the distance is about 0.3m, namely determined according to different pile diameters, and the distance between the bottom parts of the well point pipes which are radially outward is controlled to be about 0.8 m;

when accumulated water and sediment flushed out of the pile hole increase to be incapable of being constructed, the punching is suspended, accumulated water is waited to seep downwards, and the sediment is dug out;

repeating the processes of punching, well point pipe descending and sand filling until the well point pipe is descended around the bottom of the pile hole;

(3) and installing and arranging a precipitation device: assembling and connecting a well point pipe and a flexible water collecting pipe by using a connecting pipe, fixing the flexible water collecting pipe by the outer step of the retaining wall, descending a submersible jet vacuum pump by using a winch, installing the submersible jet vacuum pump close to the concrete retaining wall of the pile hole, and connecting the flexible water collecting pipe through a water suction port of the submersible jet vacuum pump; (the flexible water collecting pipe is connected with the lengthening pipe and the displacement sinking allowance of the pump barrel is reserved)

Injecting water into a pump barrel of the submersible jet vacuum pump, mounting a small submersible pump in the pump barrel, connecting the submersible jet vacuum pump and a power supply of the small submersible pump, starting the submersible jet vacuum pump to pump water, and starting the small submersible pump to drain water after observing normal pumping;

(4) precipitation, hole digging and concrete supporting processes: according to the water level descending condition, the digging hole can dig at the outer side of the pump barrel and stop when meeting the water surface, and the digging hole cannot exceed the water surface;

stopping digging and stopping the pump when the digging depth reaches 0.5m, slightly lifting the pump barrel by using a winch, swinging the pump barrel to a sinking position by a hole digging person, and sinking the pump barrel into a newly dug pit by using the winch; at the moment, starting a submersible jet vacuum pump to pump water, starting a small submersible pump to drain water, excavating sandy soil at the original pump barrel part in hole excavating operation, and controlling the height of the concrete retaining wall to be about 0.5m at a quicksand layer part;

when the position of the sand flow layer is excavated to 0.5m, stopping excavating, performing concrete supporting construction, and driving a well point pipe into a concrete retaining wall;

after the first-step concrete retaining wall of the flowing sand layer is finished and the hole digging safety requirement of the hole digging pile is met, hole digging is continued in the process, when the hole digging is carried out for 0.5m or is close to the water surface, the pump is stopped → the pump is moved → the pump is opened, the other side is dug downwards, (the precipitation depth can be controlled by about 1.0m generally by one-time pipe insertion precipitation) and concrete supporting construction is carried out after the bottom surface of the pump barrel; at this point, one process of quicksand layer precipitation, hole digging and concrete support is finished;

repeating the processes of dewatering, digging holes and concrete supporting, wherein the dewatering operation needs to be continuously carried out until the quicksand layer passes through or digs the holes to the designed pile hole depth;

finally, after the quicksand treatment is finished, digging the hole to the designed pile hole depth, continuing to maintain precipitation until the pile hole is qualified for inspection, stopping the pump before preparing to put the reinforcement cage, and withdrawing the submersible jet vacuum pump, the small submersible pump and the drain pipe in the pile hole; the flexible water collecting pipe and the connecting pipe are removed, so that pile hole accidents caused by too early pump stopping are prevented.

The punching steel pipe is outwards inclined along the water surface part of the sand flowing layer at the bottom of the protective wall to punch, the angle between the inclination of the punching steel pipe and the plumb line is 25-35 degrees, and the aperture phi is controlled to be 90-110 mm during punching.

The water suction port of the submersible jet vacuum pump is connected with a flexible water collecting pipe, the flexible water collecting pipe is connected with an extension pipe, and displacement and sinking allowance of a pump barrel is reserved.

The dewatering, excavating and concrete supporting process comprises the following steps:

well point pipes, connecting pipes and flexible water collecting pipes which are installed in the first step of precipitation are completely reserved and are not detached for the time, the condition is observed in the next step of falling sand layer precipitation, and when a water-resisting layer does not exist in the falling sand layer, after the second step of precipitation starts, the upper falling sand layer is free of water; when a water-resisting layer exists in the quicksand layer, after the first-step quicksand layer precipitation is stopped, if water continuously gushes out from the well point pipe, the water is led out into the pump barrel through the flexible water collecting pipe to be discharged, the pump barrel moves downwards along with the continuous downward digging, the flexible water collecting pipe can be lengthened, and the siphon water pumping effect is achieved.

Compared with the prior art, the invention has the following substantial characteristics and remarkable effects:

the invention is suitable for treating various quicksand layers encountered by the dug pile. The method can be used for treating the quicksand layer whether the quicksand layer is positioned at any part of a pile hole, whether the quicksand layer is predicted in advance or occurs suddenly when a hole is dug, and whether the quicksand layer is one layer or multiple layers.

According to the invention, the operation is completely carried out under the condition of no flowing sand during hole digging after the treatment of the convection sand layer, and because the precipitation process is in a vacuum negative pressure state, the precipitation sand layer is more stable under the negative pressure state, the operation can be carried out according to the work in the spot during hole digging, and the construction safety coefficient is higher.

The principle of treating the quicksand layer is a vacuum dewatering principle (a light well point dewatering principle), the principle is universal, the equipment is simple, easy and light to manufacture and easy to operate and use, and the installation of the well point pipe, the flexible water collecting pipe and the submersible jet vacuum pump in the hole digging pile can be mastered only by carrying out simple training and guidance on hole digging operators.

The cost for treating the quicksand is low, the submersible jet vacuum pump and the flexible water collecting pipe can be reused, and only well point pipes, a small amount of water for sand washing, the power cost (the total power is 5-8 kw) of the submersible jet vacuum pump and the small submersible pump and the labor cost of operators are actually consumed.

The submersible jet vacuum pump is directly arranged on the water surface of the quicksand layer, so that the dewatering efficiency is high, the dewatering speed is high, and meanwhile, the submersible jet vacuum pump is more suitable for simultaneously treating quicksand by a plurality of pile holes, can generate a group well dewatering effect, accelerates the quicksand treatment speed and improves the construction efficiency.

The invention has the defect that the operation space of hole digger is too small after the pile diameter of the manual hole digging pile is less than 1.2m, thus being not suitable for use.

Drawings

Fig. 1 is a schematic view of a punching apparatus and arrangement for processing quicksand in the present invention.

Fig. 2 is a schematic view of a flexible collector pipe of the precipitation device for treating quicksand according to the present invention.

Fig. 3 is a schematic view of a precipitation device (submersible jet vacuum pump) and arrangement for treating quicksand.

FIG. 4 is a schematic diagram of a dewatering device (submersible jet vacuum pump) for treating quicksand after pump sinking.

In the figure: the device comprises a quicksand layer 1, a connecting pipe 2, a flexible water collecting pipe 3, a concrete retaining wall 4, a winch 5, a cable 6, a power distribution cabinet 7, a drain pipe 8, a reservoir 9, a drainage pump 10, a submersible jet vacuum pump water suction port 11, a submersible jet vacuum pump 12, a quicksand layer water level 13, a well point pipe 14, washed sand 15, a quicksand layer water level 16 after precipitation, a water filtering pipe 17, a small water feeding submersible pump 18, a water feeding pipe 19 and a punched steel pipe 20

Flexible water collecting pipe device 3: a plug 301, a steel wire pipe (or plastic pipe) 302, a three-way pipe 303 and a three-way branch pipe 304.

Detailed Description

The following detailed description of the invention refers to the accompanying drawings

Light well point dewatering treatment manual hole digging pile hole digging device for generating quicksand

1. Punching device

As shown in FIG. 1, the punching device and arrangement for processing quicksand in the invention are schematic. The punching device for treating the quicksand comprises a connecting pipe 2, a flexible water collecting pipe device 3, a winch 5, a cable 6, a power distribution cabinet 7, a reservoir 9, a well point pipe 14, washed sand 15, a water filter pipe 17, a small water feeding submersible pump 18, a water feeding pipe 19 and a punching steel pipe 20; the winch 5 is arranged on the ground of the hole opening of the bored pile, and the winch 5 is used for in-hole soil discharging of the bored pile and conveying equipment to the hole bottom and is shared with hole digging and concrete dado operation; a power distribution cabinet 7 and a reservoir 9 are arranged on the ground; when the hole of the dug pile meets a quicksand layer (such as the position of 13 water level of the quicksand layer), the safe construction cannot be continued, and the quicksand layer needs to be treated, the continuous downward digging is stopped, and the hole digging operators make the concrete retaining wall 4 in the dug pile hole on the quicksand layer.

The small water-feeding submersible pump 18 is arranged in the reservoir 9 and is powered by a power distribution cabinet 7 and a cable 6 on the ground; the water-feeding submersible pump 18 is connected with the punched steel pipe 20 through a water-feeding pipe 19, and water is fed through the small-sized water-feeding submersible pump 18 for punching the quicksand layer.

A well point pipe 14 (which is well inserted with the water filter pipe 17 on the ground) is inserted into a hole punched out of the flowing sand layer, and the outside of the well point pipe is filled with water washing sand 15, wherein the well point pipe 14 is a 4-6 minute steel pipe (or a PVC pipe); the connecting pipe 2 is a plastic pipe with the inner diameter matched with the outer diameter of the well point pipe and the outer diameter of the branch pipe of the flexible water collecting pipe; the well point pipe 14 is a (4-6) steel pipe (or PVC pipe), the upper part of the well point pipe is tightly inserted with the connecting pipe 2, and the lower part of the well point pipe is tightly inserted with the water filtering pipe 17.

The strainer 17 is a plastic pipe with the inner diameter matched with the outer diameter of the well point pipe 14, and a strainer hole bag strainer is arranged on the strainer 17 and is firmly bound by a thin iron wire.

The well point pipes 14 and the strainer pipes 17 are inserted and connected, a plurality of the well point pipes are uniformly distributed in the hole of the dug pile, each well point pipe is obliquely and downwards inserted into a well point hole punched out from a quicksand layer, and the punching angle is inclined to the plumb line by about 30 degrees outwards; the washing sand 15 is filled in the peripheral holes of the well point pipe 14 and the strainer 17.

As shown in fig. 2, a flexible header assembly. The flexible water collecting pipe is formed by tightly inserting a plurality of sections of steel wire pipes (or plastic pipes) 302 with the inner diameter phi of 40 left and right and a plurality of three-way pipes 303 matched with each other.

One end of the flexible water collecting pipe 3 is sealed by a plug 301, the other end of the flexible water collecting pipe is tightly inserted with the water suction port 11 of the submersible jet vacuum pump, and the outer diameter of each branch pipe 304 is the same as that of the well point pipe 14 and is tightly inserted through the connecting pipe 2.

2. Dewatering device for treating quicksand

As shown in FIG. 3, the invention relates to a dewatering device (a submersible jet vacuum pump 12 and a small-sized drainage submersible pump 10) for treating quicksand. The dewatering device for treating quicksand comprises a connecting pipe 2, a flexible water collecting pipe 3, a winch 5, a cable 6, a power distribution cabinet 7, a drain pipe 8, a reservoir 9, a drainage pump 10, a well point pipe 14, washed sand 15 and a water filtering pipe 17.

A winch 5 is arranged on the ground of the hole opening of the bored pile, and the winch 5 is used for in-hole soil discharging of the bored pile and conveying equipment to the bottom of the hole, and is shared with hole digging and concrete supporting operation; a power distribution cabinet 7 and a reservoir 9 are arranged on the ground; when the hole of the hole digging pile meets a quicksand layer (such as the position of 13 water level of the quicksand layer), the safe construction can not be continued, and the quicksand layer needs to be treated, the downward digging is stopped, and hole digging operators make a concrete retaining wall 4 in the hole digging pile hole on the quicksand layer; after the well point pipe is installed, the flexible water collecting pipe 3 is arranged at the bottom of the pile hole and is abutted against the concrete retaining wall.

The submerged jet vacuum pump 12 is hung into the hole bottom of the dug pile by using a winch and is stably placed close to the concrete retaining wall, and the water suction port 11 is tightly inserted with the flexible water collecting pipe 3; the drainage pump 10 is arranged at the upper part in the pump barrel of the submersible jet vacuum pump, the water outlet is connected with the drainage pipe 8, and the drainage pump 8 drains the water in the quicksand layer pumped by the submersible jet vacuum pump 12 into the water reservoir 9 on the ground through the drainage pipe 8.

The submersible jet vacuum pump is a failed utility model (a submersible jet vacuum pump, patent number ZL01233751.X patent application No. 2001, 8, 3), the jet pump is simple in structure and easy to manufacture, and can be manufactured according to the pile diameter of a bored pile, the height of a control jet pump barrel is about 1.10m, and the diameter phi of the pump barrel is 400-600 cm, so that the submersible jet vacuum pump is suitable.

Second, method for treating quicksand in hole digging of manual hole digging pile through light well point dewatering

Firstly, a punching and dewatering device for treating the quicksand in the hole digging of the manual hole digging pile by using light well point dewatering. When the hole of the hole digging pile meets a quicksand layer, the safe construction cannot be continued, and the quicksand layer needs to be processed, the downward digging is stopped, and the hole digging operator does well the concrete retaining wall on the upper part of the quicksand layer.

Secondly, punching: as shown in figure 1, digging quicksand in the middle of a pile hole, digging a water collecting pit, connecting the ground, installing a small submersible pump 18, a water delivery pipe 19 and a punching steel pipe 20, putting the punching steel pipe into the pile hole of the dug pile, outwards inclining the water surface part of the quicksand layer at the bottom of a concrete retaining wall by about 30 degrees, punching, controlling the aperture phi to be about 100mm, knowing and mastering the thickness of the quicksand layer through the punching process, stopping downwards punching if the hole depth is not 1.50m and not reaching the bottom of the sand layer, and determining that the hole depth of a first step point is 1.5m (if a water-proof interlayer is not found in the punching process, the punching steel pipe can be lengthened and the hole depth can be increased according to the actual situation). If the quicksand layer is only one layer and the thickness is not large, the quicksand layer can penetrate through about 0.2m (the lower part of the quicksand layer is a soil layer) during punching,

if the bottom of the sand layer is a rock stratum, the hole is punched until the rock stratum is not moved. Inserting well point pipe 14 and strainer 17 into ground, and placing washed sand (bagged) into pile hole;

and (3) punching as described above, keeping the hole depth after the hole depth is 1.5m, after the punching water is clear, putting a 1.50m long well point pipe, stopping punching, and filling washing sand around the well point pipe in the hole, wherein the pipe head is about 10cm higher than the water surface. The well point spacing is about 30cm (determined according to different pile diameters, the bottom spacing of the radially outward well point pipes is controlled to be about 80 cm), and the punching, the pipe descending and the sand washing are repeated;

when accumulated water and sediment flushed out of the pile hole increase to be incapable of being constructed, the punching can be suspended, and the sediment is dug out while the accumulated water is leaked; and repeating the processes of punching, pipe descending and sand washing until the periphery of the bottom of the pile hole is descended into the well point pipe.

Thirdly, installing and arranging a precipitation device: according to the condition of a pipe at a well entering point, a connecting pipe is used for connecting the pipe at the well entering point and a flexible water collecting pipe, the flexible water collecting pipe 3 is fixed by a step outside a concrete protective wall (shown as a schematic diagram 1), a small-sized winch equipped with a digging hole is used for descending a submersible type jet vacuum pump 12 (the mass is less than 100kg when water is not injected into a pump barrel, and the mass is less than 300kg after water injection), the submersible type jet vacuum pump is tightly arranged on the pile hole protective wall 4, the flexible water collecting pipe 3 is connected through a water suction port 11 of the submersible type jet vacuum pump (the flexible water collecting pipe is connected with an extension pipe, and displacement and sinking allowance of the pump barrel are reserved) → water injection into the pump barrel, a small-sized submersible pump is arranged in the pump barrel, the submersible type jet vacuum pump is connected with the submersible type;

fourthly, precipitation, hole digging and concrete supporting processes: according to the water level descending condition, the digging hole can dig at the outer side of the pump barrel and stop when meeting the water surface, and the digging hole cannot exceed the water surface; when the excavation depth reaches 0.5m, stopping excavation (from the safety perspective, preventing the sand layer below the pump barrel from collapsing), stopping the pump, slightly lifting the pump barrel (the submersible jet vacuum pump 12) by using the winch 5, swinging the pump barrel to a sinking position by a hole digger, and sinking the pump barrel 12 into a newly excavated pit by using the winch 5 (see a schematic diagram 4); starting a submersible jet vacuum pump 12 to pump water, starting a small submersible pump 10 to drain water, starting a hole digging operation to dig sandy soil at the position of an original pump barrel → controlling the height of a retaining wall at the position of a quicksand layer to be about 0.5m, stopping digging after a pile hole is dug at the position of the quicksand layer to reach 0.5m, and performing retaining wall process construction (hole digging operators can continue to dig downwards under the condition of ensuring safety according to actual conditions to increase the height of the concrete retaining wall, but the digging depth of each time does not exceed the bottom of the pump barrel by 0.5m), and driving a well point pipe into the concrete retaining wall; after the first-step retaining wall of the quicksand layer is finished and the hole digging safety requirement of the hole digging pile is met, hole digging is continued in the process, and when the hole digging is carried out for 0.5m or is close to the water surface (the precipitation depth can be controlled to be about 1.0m generally by one-time pipe inserting precipitation), the pump is stopped → the pump is moved → the pump is opened, the other side of the hole digging is carried out to the bottom surface of the pump barrel, and then wall protection construction is carried out; and at this point, the process of dewatering the quicksand layer and digging the hole and protecting the wall is finished. Next, the dewatering operation is repeated, except that the dewatering process needs to be continuously carried out, and a pump barrel needs to be moved in the installation process of the well point pipe and the flexible water collecting pipe; after the installation is finished, the pump is stopped, and the flexible water collecting pipe 3 which is spliced with the water suction port 11 of the submersible jet vacuum pump is disassembled to be connected with a newly installed flexible water collecting pipe. And (5) starting a pump to pump water and drain water, and entering the next process of dewatering, excavating and supporting concrete of the quicksand layer of the bored pile.

Firstly, well point pipes (which are driven into a concrete retaining wall), connecting pipes and flexible water collecting pipes are completely reserved and are not detached for the moment, the condition is observed in the next step of quicksand layer dewatering, and when no water-resisting layer exists in the quicksand layer;

after the second step of precipitation begins, the upper quicksand layer is anhydrous; when a water-resisting layer exists in the quicksand layer, after the first-step quicksand layer precipitation is stopped, water can continuously flow out of the well point pipe, when water flows out, the water can be led out of the pump barrel through the flexible water collecting pipe to be discharged, and along with the continuous downward digging, the pump barrel moves downward, the flexible water collecting pipe can be lengthened, and the siphoning water pumping effect is achieved.

The process of precipitation, hole digging and concrete support is continued until the quicksand layer passes through or the hole is dug to the designed hole depth. When a plurality of stake holes carry out precipitation operation simultaneously, precipitation treatment quicksand effect is better.

And finally, after the quicksand treatment is finished, after the hole of the dug pile is dug to the designed hole depth, continuously maintaining precipitation until the pile hole is qualified for inspection, stopping the pump before preparing to lower the reinforcement cage, withdrawing the submersible jet vacuum pump, the small submersible pump and the drain pipe in the pile hole, and removing the flexible water collecting pipe and the connecting pipe to prevent the pile hole accident caused by too early pump stopping.

Claims (4)

1. The utility model provides a method that light-duty well point dewatering handled artifical hole digging pile hole and appears shifting sand, adopts hole digging pile hole digging to handle punching a hole and dewatering device of shifting sand when running into the sandy stratum, its characterized in that:

(1) firstly, a punching and dewatering device for treating quicksand in the dug hole of the manual dug pile by using light well point dewatering; when the hole digging of the hole digging pile meets a quicksand layer, the safe construction cannot be continued, and the quicksand layer needs to be processed, the continuous downward digging is stopped, and a hole digging operator does well a concrete retaining wall on the upper part of the quicksand layer;

(2) punching: digging quicksand in the middle of a pile hole, digging a water collecting pit, connecting and installing a small submersible pump, a water feeding pipe and a punching steel pipe on the ground, putting the punching steel pipe into the pile hole, and punching the punching steel pipe in an outward inclined manner along the water surface part of the quicksand layer at the bottom of the retaining wall; knowing and mastering the thickness of the quicksand layer through a punching process;

if the hole depth is 1.50m and does not reach the bottom of the sand layer, stopping downwards punching, and determining the hole depth of the first step point to be 1.5 m; namely, if a waterproof interlayer is not found in the punching process, lengthening the punched steel pipe according to the actual condition, and increasing the hole depth;

if the quicksand layer is only one layer and the thickness is not large, and the lower part is a soil layer, the quicksand layer penetrates 0.2m when the hole is punched, namely the lower part of the quicksand layer is the soil layer;

if the bottom of the sand layer is a rock stratum, punching the hole until the rock stratum is not moved; inserting well point pipes and filter pipes on the ground, and putting washed sand (bagged) into the pile holes;

after the hole is punched and the hole depth is 1.5m, keeping the hole depth, after the punching water is clear, putting a long well point pipe with the length of 1.5m into the hole, enabling the pipe head to be 0.1m higher than the water surface, stopping punching, and filling washing sand around the well point pipe in the hole; the distance is about 0.3m, namely the distance is about 0.8m according to the determination of different pile diameters and the bottom of the well point pipe which is radially outward is controlled;

when accumulated water and sediment flushed out of the pile hole increase to be incapable of being constructed, the punching is suspended, and the sediment is dug out while the accumulated water is leaked;

repeating the processes of punching, well point pipe descending and sand filling until the well point pipe is descended around the bottom of the pile hole;

(3) and installing and arranging a precipitation device: assembling and connecting a well point pipe and a flexible water collecting pipe by using a connecting pipe, fixing the flexible water collecting pipe by the outer step of the retaining wall, descending a submersible jet vacuum pump by using a winch, installing the submersible jet vacuum pump close to the concrete retaining wall of the pile hole, and connecting the flexible water collecting pipe through a water suction port of the submersible jet vacuum pump;

injecting water into a pump barrel of the submersible jet vacuum pump, mounting a small submersible pump in the pump barrel, connecting the submersible jet vacuum pump and a power supply of the small submersible pump, starting the submersible jet vacuum pump to pump water, and starting the small submersible pump to drain water after observing normal pumping;

(4) precipitation, hole digging and concrete supporting processes: according to the water level descending condition, the digging hole can dig at the outer side of the pump barrel and stop when meeting the water surface, and the digging hole cannot exceed the water surface;

stopping digging and stopping the pump when the digging depth reaches 0.5m, slightly lifting the pump barrel by using a winch, swinging the pump barrel to a sinking position by a hole digging person, and sinking the pump barrel into a newly dug pit by using the winch; at the moment, starting a submersible jet vacuum pump to pump water, starting a small submersible pump to drain water, excavating sandy soil at the original pump barrel part in hole excavating operation, and controlling the height of the concrete retaining wall to be about 0.5m at a quicksand layer part;

when the position of the sand flow layer is excavated to 0.5m, stopping excavating, performing concrete supporting construction, and driving a well point pipe into a concrete retaining wall;

after the first-step concrete retaining wall of the flowing sand layer is finished and the hole digging safety requirement of the hole digging pile is met, hole digging is continued in the process, when the hole digging is carried out for 0.5m or is close to the water surface, the pump is stopped → the pump is moved → the pump is started, the other side of the hole digging pile is dug downwards, and concrete supporting construction is carried out after the bottom surface of the pump barrel is reached; at this point, one process of quicksand layer precipitation, hole digging and concrete support is finished;

repeating the processes of dewatering, digging holes and concrete supporting, wherein the dewatering operation needs to be continuously carried out until the quicksand layer passes through or digs the holes to the designed pile hole depth;

finally, after the quicksand treatment is finished, digging the hole to the designed pile hole depth, continuing to maintain precipitation until the pile hole is qualified for inspection, stopping the pump before preparing to put the reinforcement cage, and withdrawing the submersible jet vacuum pump, the small submersible pump and the drain pipe in the pile hole; the flexible water collecting pipe and the connecting pipe are dismantled, and pile hole accidents caused by early pump stop are prevented.

2. The method for treating the quicksand in the dug hole of the manual dug pile by using the light well point dewatering as claimed in claim 1, wherein the method comprises the following steps: the punching steel pipe is outwards inclined along the water surface part of the sand flowing layer at the bottom of the protective wall to punch, the angle between the inclination of the punching steel pipe and the plumb line is 25-35 degrees, and the aperture phi is controlled to be 90-110 mm during punching.

3. The method for treating the quicksand in the dug hole of the manual dug pile by using the light well point dewatering as claimed in claim 1, wherein the method comprises the following steps: the water suction port of the submersible jet vacuum pump is connected with a flexible water collecting pipe, the flexible water collecting pipe is connected with an extension pipe, and displacement and sinking allowance of a pump barrel is reserved.

4. The method for treating the quicksand in the dug hole of the manual dug pile by using the light well point dewatering as claimed in claim 1, wherein the method comprises the following steps: the dewatering, excavating and concrete supporting process comprises the following steps:

well point pipes, connecting pipes and flexible water collecting pipes which are installed in the first step of dewatering are completely reserved and are not detached for the time, and the condition is observed in the next step of the quicksand layer dewatering process;

when the quicksand layer is not provided with a water-resisting layer, after the second-step precipitation is started, the upper quicksand layer is free of water;

when a water-resisting layer exists in the quicksand layer, after the first-step quicksand layer precipitation is stopped, if water continuously gushes out from the well point pipe, the water is led out into the pump barrel through the flexible water collecting pipe to be discharged, the pump barrel moves downwards along with the continuous downward digging, the flexible water collecting pipe can be lengthened, and the siphon water pumping effect is achieved.

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