CN103938637B - Rigid-flexible combined pile foundation pit supporting construction method for hard-layer soft soil geology - Google Patents

Abstract

The invention discloses a foundation pit supporting construction method for a rigid-flexible combined pile in a hard-layer soft soil geology. And (3) utilizing a rotary drilling hole to penetrate through the hard interlayer, pumping out concrete from the bottom of the drill bit by virtue of the rotary blade when drilling to the designed depth, and simultaneously pouring and lifting the drill rod to the ground so as to form the pump pressure plain concrete pile. And then, hoisting the connected vibration device, the high-rigidity core pipe and the steel reinforcement cage, inserting the lower end of the steel reinforcement cage into the concrete pile body, and driving the high-rigidity core pipe to vibrate the lower end of the steel reinforcement cage by means of gravity and the vibration device to enable the steel reinforcement cage to sink to the designed depth, so that the rigid pile is formed. The flexible pile is constructed firstly, then the rigid pile is constructed, the rigid pile and the flexible pile are arranged in a meshed mode to form a waterproof curtain, and the rigid pile not only plays a role in water stopping, but also plays a role in slope protection.

Description

Construction method of rigid-flexible combined pile foundation pit support in soft soil with interlayer hard layer

technical field

The invention relates to a construction method for foundation pit support, in particular to a construction method for foundation pit support with rigid-flexible combination piles in soft soil interlayer.

Background technique

Water-stop curtains in soft soil areas often use cement-soil mixing piles or rotary grouting piles. However, when encountering gravel, pebbles and other strata, the drill bits of cement-soil mixing piles or rotary grouting piles cannot penetrate hard layers and cannot reach the design depth. The traditional foundation pit support method usually adopts the method of separately setting the water-stop curtain and the slope protection pile. The water-stop curtain is generally set on the outside, and the slope protection pile is set on the inside. The number of piles will be large, and the cost of foundation pit support will be high. The present invention improves this. The flexible pile is placed in the middle of adjacent rigid piles. On the one hand, the flexible pile and the rigid pile cooperate to deform as a support structure; The effect is reliable. From an economic point of view, it is obvious that the number of piles is much lower than the traditional one, thus saving the project cost.

Contents of the invention

The technical problem to be solved by the present invention is to provide a construction method for foundation pit support of rigid-flexible combined piles in interlayer soft soil, which solves the problem of high cost of traditional foundation pits.

Process principle of the present invention adopts as follows:

Use rotary drilling to pass through the hard interlayer, and when drilling to the designed depth, use the rotary blade to cut the soft soil, and lift the drill pipe while rotating the grout to form a flexible pile. Use rotary drilling to pass through the hard interlayer, and when drilling to the design depth, pump the concrete from the bottom of the drill bit with the help of rotary blades, and lift the drill pipe to the ground while pouring, thus forming a pumped plain concrete pile. Then lift the connected vibrating device, high rigidity core tube and reinforcement cage, insert the lower end of the reinforcement cage into the concrete pile, rely on the gravity and the vibration device to drive the high rigidity core tube to vibrate the lower end of the reinforcement cage, so that the reinforcement cage sinks to Design the depth so that a rigid pile is formed. The flexible piles are constructed first, and then the rigid piles are constructed. The rigid piles and flexible piles are occluded and arranged to form a water-stop curtain. The rigid piles not only play the role of water-stop, but also play the role of slope protection.

Construction steps of the present invention include:

1. Measurement and setting-out positioning

After cleaning the construction site, the base point and baseline provided by Party A should be retested. After confirming that they are correct, the specific pile positions should be released according to the base point and baseline. The minimum is 10mm, and the measurement record should be done well, and the construction can only be carried out after it is accurate.

2 rigs in place

The drilling rig should be kept stable to ensure that no tilting movement occurs during construction. In order to accurately control the drilling depth, a control scale should be set on the frame for observation.

3 drilling rig lead hole

If the verticality of the pile does not meet the requirements, the water-stop curtain at the bottom of the pile will leak, and the water-stop effect will not be achieved. In order to control the verticality of the pile, the following measures are taken: on the slideway of the pile frame of the drilling rig, two casings with directional function are installed, and the inner diameter is only 10mm larger than the diameter of the drill pipe, which solves the problem of friction and swing of the drill pipe. Set up a self-made gravity verticality instrument at the bottom of the tappet. After the pile position is centered, put a sleeper on the bottom of the tappet and compact it to ensure that when the tappet swings under force, the self-locking device around the axis of the drilling rig and the friction generated by the tappet and the sleeper resist the swing, so that the pile position does not change. . After aligning the pile center and adjusting the verticality of the drill pipe, use theodolite to check the verticality of the drill pipe again, and monitor it at any time during the drilling process to ensure that the positioning error is less than 5mm and the construction error is less than 10mm.

4 side drilling pumping cement slurry

After drilling to the predetermined depth, it must be idling at the bottom of the hole to clear the soil, then stop the rotation, lift the drill to the ground while pumping the cement slurry, and rotate at a constant speed when lifting the drill to make the pumped cement slurry and soil evenly mixed to form a Flexible pile. The drilling speed in the soft soil layer is 0.8-1m/min, and the drilling speed in the hard interlayer should be slowed down, and the drilling speed is 0.2-0.4m/min. If the drilling rig shakes, the drilling speed should be slowed down.

5 pressure poured concrete

Immediately after the completion of the construction of the flexible pile, drill the hole at the design position of the rigid pile. After drilling to the predetermined depth, the soil must be idly cleared at the bottom of the hole, and then stop the rotation. Lift the drill to the ground while pumping the concrete. Do not rotate when lifting the drill. And keep lifting at a constant speed to ensure that the drill bit is always buried in the concrete to prevent the pile from breaking. Since the occlusal part of rigid pile and flexible pile may have certain strength, the drilling speed should be slowed down. It is 0.1～0.3m/min. If the drilling rig shakes, the drilling speed will be slowed down.

6 Insert the reinforcement cage

After the concrete is poured, the steel cage is inserted into the concrete by a vibrating device to form a rigid pile. The vibrating device adopts a medium and low frequency vibrating hammer, and a vibration isolating device is installed; there is a lifting ring on the top of the vibrating hammer, which is used to lift the vibrating device and the high-rigidity core tube; the steel cage alignment ring is used to fix and align the steel cage; The sling is tied to the vibrating hammer and used for lifting by a crane. At the same time, people are used to operate it to ensure the verticality of the reinforcement cage; 2 to 4 steel rings are welded on the lower part of the vibrating hammer and the reinforcement cage, which are inserted into the wire rope and clamped to lift the reinforcement. Cage and position. The high-rigidity core tube is connected to the vibrating device with a flange, the lower end of the high-rigidity core tube is pressed against the end of the steel cage, the upper end of the steel cage is flexibly connected to the vibrating device, the lower end of the high-rigidity core tube is open, and air holes are opened in the middle and upper parts.

7 Make pile top concrete pressure beam

The strength of the pile top concrete pressure beam is C25 or C30, and the pile top concrete pressure beam is provided with a reserved hole at the anchor rod to facilitate drilling by the drilling rig.

8 Anchor construction

The down-the-hole drilling rig is used to drill holes according to the design inclination, the error of the hole distance is not greater than 150mm, and the error of the hole depth is not greater than 50mm. After the drilling is completed, use a mortar pump to pour cement slurry into the hole, and the grouting pressure is 0.1-0.2MPa. When grouting, the grouting pipe should be inserted about 100mm from the bottom of the hole, and slowly pulled out with the grout injection until the borehole is full. The rebar body is then inserted into the drilled hole filled with grout.

9 Shotcrete for the first time

Bury short φ6 steel bars with thickness control marks, wash the slope with high-pressure water, and moisten the surface of the slope. First dry mix the cement, sand and gravel according to the mixing ratio, then sieve and load them into the spraying machine, and then start spraying the first layer of concrete. The spraying operation should be carried out in sections and pieces, from top to bottom. When spraying, the nozzle should be perpendicular to the surface to be sprayed, keeping a distance of 0.8m ~ 1.0m, and the hand-held spray gun should be rotated evenly to ensure that the sprayed concrete is dense and uniform. . At the same time, the water-cement ratio should be well controlled, the rebound rate should not be greater than 15%, and the sprayed concrete should be sprayed with water for curing after 2 hours of final setting.

10 hanging wire mesh

Bind the straightened φ6 steel bars into steel mesh sheets with thin iron wires, and the intersection points of the steel mesh should be tied firmly.

11 Second shotcrete

Rinse off the first coat of shotcrete with high pressure water and wet the surface. The second layer of concrete spraying sequence and operation method is the same as the first layer. When starting to spray, the distance between the nozzle and the sprayed surface should be reduced, and the spray angle should be adjusted to ensure the compactness of the second layer of sprayed concrete. If the concrete falls off due to being supported by the steel mesh during spraying, it should be removed in time. Spraying personnel should adjust the water supply valve of the spray gun to control the water-cement ratio, so that the concrete surface is smooth, moist and shiny, and there is no flow and dry spots. After 2 hours of final setting of shotcrete, spray water for 7 days. The number of water sprays per day should be sufficient to keep the shotcrete surface wet.

The cement used for the flexible pile is ordinary Portland cement, the grade is 42.5, the mixing amount is 15%, and the water-cement ratio is 1.0. The water used for cement slurry must be clean and pollution-free, and the cement slurry should be prepared about 30 minutes before grouting. Stir fully in the agitator, and then flow out from the slurry outlet after stirring evenly, and filter through a filter to remove unhydrated particles and impurities in the slurry. The filtered grout enters the mud pump and is pumped into the grouting pipe.

The cement used for the rigid pile is ordinary Portland cement, the grade is 42.5, and the water-cement ratio is 0.45-0.5. The fine aggregate is selected from natural medium and coarse sand with reasonable gradation, hard texture and pure particles; the coarse aggregate is selected from hard pebbles or crushed stones, with a particle size of 5mm to 15mm.

The quality control measures in the construction process are as follows:

1 When the drilling rig is in place, it must be flat and stable, and the vertical deviation should not exceed 1%.

2 The reinforcement cage is composed of the main reinforcement and the transverse stirrup, and the reinforcement is set every 2m or so. The thickness of the protective layer of the main reinforcement of the steel cage should not be less than 35mm, and the allowable deviation of the protective layer of the main reinforcement is 10mm. Sliding shoes are added outside the main reinforcement of the steel cage to ensure the protective layer of the steel reinforcement.

3. At the bottom of the reinforcement cage, the six main reinforcements are lengthened and connected inwardly to form a bowl shape, which is used as the connection between the vibrating core tube and the reinforcement cage, and at the same time, the solder joints between the bottom horizontal stirrup and the main reinforcement are strengthened. Set 2 to 4 lifting points, and the horizontal stirrups at the lifting points should be strengthened with double hoops to avoid open welding when lifting.

4. After the rigid pile concrete is poured, the concrete strength should meet the design requirements. The concrete should set well without honeycombs, cavities, segregation, cracks, interlayers and other undesirable phenomena, and the concrete should not have debonding and exposed steel cages.

5 The concrete slump of the rigid pile should meet 180mm-220mm, and it has good workability, cohesiveness and water retention, and the initial setting time should meet the pouring time as the principle.

The present invention has significant economic benefits. The traditional method is that the water-stop structure and the soil-retaining structure are separated. Usually, flexible piles are used to form a water-stop curtain, and rigid piles are arranged inside the flexible piles to retain soil. In the present invention, the rigid piles are one On the one hand, it can retain soil and stop water. The number of rigid piles and flexible piles is far smaller than that of traditional methods, which has obvious economic benefits. In the present invention, the rigid pile and the flexible pile do not produce soil squeezing effect during construction, and almost no additional stress is generated on the foundation during construction, thereby reducing soil disturbance and having little impact on the surrounding environment.

The invention has the following characteristics: the construction quality is easily guaranteed, and the engineering cost is low. The construction vibration and noise are small, the impact on the surrounding environment is small, the construction period is short, and the support effect is good. The invention is suitable for foundation pit support under soft ground conditions with hard interlayers such as crushed stones or pebbles in the shallow layer.

Description of drawings

Fig. 1 is a process flow diagram, and Fig. 2 is a schematic plan view of the arrangement of rigid piles and flexible piles.

Reference signs: 1, rigid pile, 2, flexible pile.

detailed description

The present embodiment will be described in detail below in conjunction with the accompanying drawings.

Wenzhou Chengfeng Building is 33m high, with a total construction area of 57,880m ² . It adopts a frame shear wall structure. The foundation pit excavation depth of the project is 5.3m, and the excavation area of the foundation pit is about 5,330m ² . The geological report shows that the site soil is about 8m. For the crushed stone interlayer with a thickness of about 0.8-1.5m, the foundation pit support adopts the construction method of rigid-flexible pile foundation pit support.

Figure 1 is a process flow chart, and the construction steps include:

1. Measurement and setting-out positioning

After cleaning the construction site, the base point and baseline provided by Party A should be retested. After confirming that they are correct, the specific pile positions should be released according to the base point and baseline. The minimum is 10mm, and the measurement record should be done well, and the construction can only be carried out after it is accurate.

2 rigs in place

The drilling rig should be kept stable to ensure that no tilting movement occurs during construction. In order to accurately control the drilling depth, a control scale should be set on the frame for observation.

3 drilling rig lead hole

If the verticality of the pile does not meet the requirements, the water-stop curtain at the bottom of the pile will leak, and the water-stop effect will not be achieved. In order to control the verticality of the pile, the following measures are taken: on the slideway of the pile frame of the drilling rig, two casings with directional function are installed, and the inner diameter is only 10mm larger than the diameter of the drill pipe, which solves the problem of friction and swing of the drill pipe. Set up a self-made gravity verticality instrument at the bottom of the tappet. After the pile position is centered, put a sleeper on the bottom of the tappet and compact it to ensure that when the tappet swings under force, the self-locking device around the axis of the drilling rig and the friction generated by the tappet and the sleeper resist the swing, so that the pile position does not change. . After aligning the pile center and adjusting the verticality of the drill pipe, use theodolite to check the verticality of the drill pipe again, and monitor it at any time during the drilling process to ensure that the positioning error is less than 5mm and the construction error is less than 10mm.

4 side drilling pumping cement slurry

After drilling to the predetermined depth, it must be idling at the bottom of the hole to clear the soil, then stop the rotation, lift the drill to the ground while pumping the cement slurry, and rotate at a constant speed when lifting the drill to make the pumped cement slurry and soil evenly mixed to form a Flexible pile. The drilling speed in the soft soil layer is 0.8-1m/min, and the drilling speed in the hard interlayer should be slowed down, and the drilling speed is 0.2-0.4m/min. If the drilling rig shakes, the drilling speed should be slowed down.

5 pressure poured concrete

Immediately after the completion of the construction of the flexible pile, drill the hole at the design position of the rigid pile. After drilling to the predetermined depth, the soil must be idly cleared at the bottom of the hole, and then stop the rotation. Lift the drill to the ground while pumping the concrete. Do not rotate when lifting the drill. And keep lifting at a constant speed to ensure that the drill bit is always buried in the concrete to prevent the pile from breaking. Since the occlusal part of rigid pile and flexible pile may have certain strength, the drilling speed should be slowed down. It is 0.1～0.3m/min. If the drilling rig shakes, the drilling speed will be slowed down.

6 Insert the reinforcement cage

After the concrete is poured, the steel cage is inserted into the concrete by a vibrating device to form a rigid pile. The planar layout of rigid piles and flexible piles is shown in Figure 2. The vibrating device adopts a medium and low frequency vibrating hammer, and a vibration isolating device is installed; there is a lifting ring on the top of the vibrating hammer, which is used to lift the vibrating device and the high-rigidity core tube; the steel cage alignment ring is used to fix and align the steel cage; The sling is tied to the vibrating hammer and used for lifting by a crane. At the same time, people are used to operate it to ensure the verticality of the reinforcement cage; 2 to 4 steel rings are welded on the lower part of the vibrating hammer and the reinforcement cage, which are inserted into the wire rope and clamped to lift the reinforcement. Cage and position. The high-rigidity core tube is connected to the vibrating device with a flange, the lower end of the high-rigidity core tube is pressed against the end of the steel cage, the upper end of the steel cage is flexibly connected to the vibrating device, the lower end of the high-rigidity core tube is open, and air holes are opened in the middle and upper parts.

7 Make pile top concrete pressure beam

The strength of the pile top concrete pressure beam is C25 or C30, and the pile top concrete pressure beam is provided with a reserved hole at the anchor rod to facilitate drilling by the drilling rig.

8 Anchor construction

The down-the-hole drilling rig is used to drill holes according to the design inclination, the error of the hole distance is not greater than 150mm, and the error of the hole depth is not greater than 50mm. After the drilling is completed, use a mortar pump to pour cement slurry into the hole, and the grouting pressure is 0.1-0.2MPa. When grouting, the grouting pipe should be inserted about 100mm from the bottom of the hole, and slowly pulled out with the grout injection until the borehole is full. The rebar body is then inserted into the drilled hole filled with grout.

9 Shotcrete for the first time

Bury short φ6 steel bars with thickness control marks, wash the slope with high-pressure water, and moisten the surface of the slope. First dry mix the cement, sand and gravel according to the mixing ratio, then sieve and load them into the spraying machine, and then start spraying the first layer of concrete. The spraying operation should be carried out in sections and pieces, from top to bottom. When spraying, the nozzle should be perpendicular to the surface to be sprayed, keeping a distance of 0.8m ~ 1.0m, and the hand-held spray gun should be rotated evenly to ensure that the sprayed concrete is dense and uniform. . At the same time, the water-cement ratio should be well controlled, the rebound rate should not be greater than 15%, and the sprayed concrete should be sprayed with water for curing after 2 hours of final setting.

10 hanging wire mesh

Bind the straightened φ6 steel bars into steel mesh sheets with thin iron wires, and the intersection points of the steel mesh should be tied firmly.

11 Second shotcrete

Rinse off the first coat of shotcrete with high pressure water and wet the surface. The second layer of concrete spraying sequence and operation method is the same as the first layer. When starting to spray, the distance between the nozzle and the sprayed surface should be reduced, and the spray angle should be adjusted to ensure the compactness of the second layer of sprayed concrete. If the concrete falls off due to being supported by the steel mesh during spraying, it should be removed in time. Spraying personnel should adjust the water supply valve of the spray gun to control the water-cement ratio, so that the concrete surface is smooth, moist and shiny, and there is no flow and dry spots. After 2 hours of final setting of shotcrete, spray water for 7 days. The number of water sprays per day should be sufficient to keep the shotcrete surface wet.

During the construction process, the foundation pit was monitored, and the monitoring results showed that the deformation of the foundation pit was within the specified range, and the surrounding roads and ground did not appear to settle, and the implementation effect was ideal.

Claims (4)

1. press from both sides a hard formation Soft Clay rigid-flexible mechanical arm base pit stand construction, it is characterized in that utilizing convolution boring through hard interbedded layer, when getting into projected depth, by swirl vanes cutting weak soil, drilling rod is carried on rotary water jet mud limit, limit, thus forms flexible pile; Utilize convolution boring through hard interbedded layer, when getting into projected depth, pumped by concrete by swirl vanes by bottom drill bit, drilling rod is carried to ground in perfusion limit, limit, thus forms pump pressure plain concrete pile; To sling subsequently the vibrating device, large rigidity core pipe and the reinforcing cage that connect, reinforcing cage lower end is inserted in concrete pile body, rely on gravity and vibrating device to drive large rigidity core pipe to vibrate reinforcing cage lower end, make reinforcing cage sink down into projected depth, thus form rigid pile; First to construct flexible pile, rigid pile of then constructing, rigid pile and flexible pile snap-fit arrangement, form water-stop curtain, rigid pile not only plays the effect of sealing, also serves the effect of bank protection;

It is characterized in that construction sequence comprises:

(1) surveying setting-out location

Cleaning construction plant after, the basic point of answering repetition measurement Party A to provide and baseline, determine errorless after, release concrete stake position according to basic point and baseline again, measuring order in stake position is undertaken by sequence of construction, and stake position should fix, the little 10mm of pile center's line deviation, and carry out surveying record, can construct after accurate;

(2) driller insertion

Held stationary answered by rig, guarantees, in construction, any inclination movement does not occur; For the accurate keyhole degree of depth, should control scale be set in frame, to observe;

(3) rig draws hole

(4) pumps water mud is crept on limit

After getting into desired depth, must carry out dallying in bottom, hole soil clearly, and then stop operating, pumps water mud limit, limit is carried and is drilled into ground, carries out uniform rotation when carrying brill, makes pumps water mud and the even mix of soil, forms flexible pile; Soft Soil Layer rate of penetration is 0.8 ~ 1m/min, and hard interbedded layer position rate of penetration will slow down, and rate of penetration is 0.2 ~ 0.4m/min, if swag phenomenon appears in rig, rate of penetration also will slow down;

(5) guncreting

At once in rigid pile design position boring after flexible pile construction, after getting into desired depth, must carry out dallying in bottom, hole soil clearly, then stop operating, pumping of concrete limit, limit is carried and is drilled into ground, must not rotate when carrying brill, and the lifting that remains a constant speed, guarantee that drill bit is embedded in concrete all the time, prevent broken pile; Because may there be certain intensity at rigid pile and flexible pile occlusion position, rate of penetration will slow down, and Soft Soil Layer rate of penetration is 0.5 ~ 0.7m/min, and hard interbedded layer position rate of penetration also will slow down, rate of penetration is 0.1 ~ 0.3m/min, if swag phenomenon appears in rig, rate of penetration slows down again;

(6) reinforcing cage is inserted

After concreting, by vibrating device, reinforcing cage is inserted concrete, form rigid pile;

(7) stake top concrete capping beam is done

Stake top concrete capping beam intensity adopts C25 or C30, and stake top concrete capping beam arranges preformed hole at anchor pole position, so that rig is holed;

(8) anchor bolt construction

Adopt down-the-hole drill to hole according to design inclination angle, pitch-row error is not more than 150mm, and hole depth error is not more than 50mm; Holed rear mortar pump to grout injection in hole, and grouting pressure is 0.1 ~ 0.2MPa; During slip casting, Grouting Pipe should be inserted apart from being about 100mm place at the bottom of hole, slowly extracts with cement paste injection, to hole full; Then being inserted by the reinforcing bar body of rod fills in the boring of cement paste;

(9) first time sprayed mortar

Bury φ 6 bar dowel controlling thickness mark underground, use high pressure water washing side slope, moistening side slope surface; First cement, sand, rubble are loaded spraying machine by after match ratio dry mixing evenly after sieve, then start to spray first floor concrete; Spraying operation is answered segmentation and slicing, is carried out successively from top to bottom, during injection shower nozzle with should be vertical by spray plane, keep the distance of 0.8m ~ 1.0m, spray pistol and do Rotating with Uniform motion, even to ensure the concrete compaction ejected; Control water/binder ratio well, rebound degree should not be greater than 15%, wet curing after sprayed mortar final set 2h simultaneously;

(10) gauze wire cloth is hung

With thin wire, φ 6 reinforcing bar binding through straightening is become reinforced mesh, the crosspoint of steel mesh reinforcement answers colligation solid;

(11) second time sprayed mortar

With water under high pressure, first floor sprayed mortar face is rinsed well and wetted surface; Second layer concrete ejection order is identical with first floor with method of operating; Shower nozzle and the distance by spray plane should be reduced when starting to spray, and adjust spray angle, to ensure the density of second layer sprayed mortar; Firmly occurred that concrete comes off if having in injection by bar frame should remove in time; Injection personnel should adjust the water supply valve of spray gun, control water/binder ratio, make concrete surface smooth, moistening gloss, without trickling dry spot phenomenon.

2. folder hard formation Soft Clay rigid-flexible mechanical arm base pit stand construction according to claim 1, it is characterized in that on the slideway of rig pile frame, arrange the casing that two have orientation, internal diameter is only greater than drill pipe diameter 10mm, solves friction and the vibration problems of drilling rod; Self-control gravity Verticality gauge is set bottom tappet; After stake position centering, bolster wood bottom tappet compacting, ensure when the stressed swing of tappet, to resist and swing, stake position is not changed by rig around the frictional force that axle self-locking device and tappet and sleeper produce; After pile center's contraposition, drilling rod Uprightness adjusting degree, detect drilling rod verticality again with transit, and monitor at any time in boring procedure, guarantee that position error is less than 5mm, construction error is less than 10mm.

3. folder hard formation Soft Clay rigid-flexible mechanical arm base pit stand construction according to claim 1, is characterized in that vibrating device adopts low and medium frequency vibrating hammer, and has installed isolation mounting; Suspension ring are arranged at vibrating hammer top, for lifting by crane vibrating device and large rigidity core pipe; Reinforcing cage aligns circle and is used to fixing and aligns reinforcing cage; Lifting rope lies on vibrating hammer, and for crane lifting, the verticality guaranteeing that reinforcing cage is laid is handled in employment simultaneously; Vibrating hammer bottom and reinforcing cage are welded with 2 ~ 4 steel loops, penetrate wire rope clamping, lifting reinforcing cage is also located; The effective flange of large rigidity core is connected on vibrating device, and large rigidity core pipe lower end is pressed in reinforcing cage end, and reinforcing cage upper end and vibrating device flexibly connect, and large rigidity core pipe lower ending opening, pore is opened at middle part, top.

4. folder hard formation Soft Clay rigid-flexible mechanical arm base pit stand construction according to claim 1, is characterized in that wet curing 7d after sprayed mortar final set 2h; Every day, the number of times of water spray should be able to keep sprayed mortar surface wettability.