CN110230309A - Karst region bridge solution cavity pile base construction method - Google Patents

Abstract

The invention discloses a kind of karst region bridge solution cavity pile base construction methods, comprising the following steps: punching and karst cave treatment repeat punching and karst cave treatment, to the last pore-forming；Karst cave treatment, which specifically includes, identifies type and process method step, wherein identify type be before starting drilling, in drilling process and in filling process, according to vertical depth and there is non-filler to judge type of cavern；Wherein processing method includes the pretreatment before construction, the processing in drilling and the processing during concrete pouring.The present invention keeps solution cavity pile foundation construction more safe and effective in different solution cavities using different disposal method；Reach and accelerate pore-forming progress, guarantees pile quality, save the purpose of construction cost.

Description

Karst region bridge solution cavity pile base construction method

Technical field

The present invention relates to karst area Bridge Pile Foundation Construction technical field more particularly to a kind of karst region bridge are molten Hole pile base construction method.

Background technique

Bridge Pile Foundation Construction positioned at karst landform area is easy to happen bit freezing, the tiltedly safety such as brill, collapse hole, surface collapse Accident.The application is disclosed using the 1st bid section Bridge Pile Foundation Construction of Wuhan City South 4th Ring Road line as background according to geology survey data The data such as solution cavity height, the solution cavity number of plies, buried depth, roof strata thickness are briefly illustrated in conjunction with the practical karst cave treatment effect in scene Pile foundation karst cave treatment method under different Karst Geological Landscape developmental morphologies.

Line the 1st bid section in Wuhan City South 4th Ring Road is mainly overhead to Beijing-Guangzhou Railway all the way by Gong Jia paving interchange overpass and industry Bridge two large divisions composition, main line overall length 5.129km.The single solution cavity height of this project discovery is few generally between 0.2m~5m Amount reaches 5m~34.5m.Single pile solution cavity total height reaches 15m~37.4m, maximum single pile solution cavity generally between 1m~15m on a small quantity Height is 69.7m.

Summary of the invention

In view of the above deficiencies, it is applied the technical problems to be solved by the present invention are: providing a kind of karst region bridge solution cavity pile foundation Work method, the solution cavity pile foundation construction of this method different geological conditions, different type of cavern, using different karst cave treatment methods, Keep solution cavity pile foundation construction more safe and effective.Reach and accelerate pore-forming progress, guarantees pile quality, save the purpose of construction cost.

In order to solve the above technical problems, the technical scheme is that

A kind of karst region bridge solution cavity pile base construction method, comprising the following steps: punching and karst cave treatment repeat Punching and karst cave treatment, to the last pore-forming；The karst cave treatment is starting to bore specifically includes the following steps: identifying type Kong Qian, in drilling process and in filling process, according to vertical depth and there is non-filler to judge type of cavern, solution cavity Type includes that karst is generally developed, karst relatively development, karst pole is developed and full packing；Processing method the treating method comprises Pretreatment before construction, the processing in drilling and the processing during concrete pouring；The pretreatment develops lava pole molten Hole, by the way of the follow-up of steel pillar, karst is generally developed, karst relatively development and full packing solution cavity is double based on cement injection Supplemented by slurry；Processing in the drilling is to backfill a certain proportion of slabstone, clay, cement, mass ratio 20:10:1； Processing during the concrete pouring is Concrete Filled.

Preferred embodiment is the concrete mode for identifying type are as follows:

Before starting drilling, base area surveys data and carries out rough estimates, and whether solution cavity is in beading point in the drilling of part Cloth determines solution cavity distribution, can also be according to sampling is surveyed in detail, and determination will spud in pier position with the presence or absence of solution cavity；According to closing on Construction pile foundation primarily determines construction area with the presence or absence of solution cavity；

In drilling process, if water level in borehole decline, cable wires at well head loosen extremely, show spillage situation occur；According to Slag specimen is analyzed, and sees whether slag specimen anomalous variation occurs；Judged according to penetration rate, in drilling process, before spillage Drilling footage notes abnormalities, fast when drilling depth is compared with normal operation in normal, in fact it could happen that full packing；According to drill bit, whether deflection is carried out Judge, finds that drill bit, wirerope deviate center in drilling process, primarily determine slope rock, small solution cavity or crack occur；

In filling process, there is larger gap in concrete top surface lifting height and theoretical lifting height, are determined as coagulation soil flow It loses, solution cavity occurs.

Preferred embodiment is, further comprising the steps of before construction: by the ground to solution cavity pile foundation of having constructed survey data, Borehole log, pore-forming time, the statistics and analysis that record, pile quality is perfused, to according to different geological conditions, different solution cavities The solution cavity pile foundation construction of type, using different karst cave treatment methods, specifically:

It is bad for coating geology, the loose stake position of soil property, by the way of lengthening aperture casing to rock stratum roof plate into Row processing；When spillage occurring in hole, according to the filler of molten chamber, height, spillage speed different situations, backfill piece is respectively adopted The method of stone clay, concrete, bagged cement squeezes slabstone by small stroke, clay mixture forms more closely knit stable shield Wall；

For large-scale single solution cavity and shaped corroded cave model, the processing mode to be followed up using full casing, steel pile casting is directly worn It crosses solution cavity and forms steel pile casting retaining wall.

Preferred embodiment is, the vertical depth of the basis and has non-filler to judge in type of cavern, specific judgment mode Are as follows: karst is generally developed, h < 3, and no filling half is filled；Karst is relatively developed, 3≤h≤5, no filling or half filling；Karst pole hair It educates, h > 5m, no filling or half filling；Full packing.

Preferred embodiment is that the pretreatment is using single liquid cement slurry slip casting pretreatment, construction method are as follows:

(1) surveying and locating: according to the control point coordinates laid, the coordinate position of pilot hole is calculated, is put using total station Hole location out measures ground elevation with level, determines pilot hole depth；

(2) drilling, Completion of Drilling Hole method include that drilling machine is in place, drilling of sinking, propose drill bit, displacement four steps work, drilling machine peace After dress is in place, keep it steady, drill bit align piles hole location, drilling of sinking；When drilling, drilling machine keeps horizontal, guarantees the gradient of stake Less than design requirement value, drilling depth should reach grouting reinforcement section, to make a record in drilling process, provide for slip casting operation Reference data；

(3) it infuses sleeve shell material, be inserted into no eyelet steel pipe in the sky, and sleeve shell material is pressed by this pipe, until mud is complete in hole It is ejected outside hole entirely, extracts steel pipe；

(4) pipe laying, mini-valve tube connected according to pilot hole depth first, the mini-valve tube 20~30cm suitable for reading that bassets will connect Mouth is good with sharp underseal under good mini-valve tube；It then, will be in mini-valve tube tripping in hole, it is to be ensured that bottom hole, worst error are arrived under mini-valve tube No more than 20cm, be such as hampered power during assigning, and when cannot smoothly be inserted into, should ascertain the reason, and forbids strong using excessive external force Row indentation, water is filled into hole, protective cap is covered and makes marks after being installed；

(5) sealing, the ground around aperture to ground are once in the distance range of 1m using accelerated cement mortar envelope It is stifled, to prevent the generation of grout phenomenon during slip casting；

(6) slip casting, sleeve shell material conserve 3 days or so, use retrusive segmenting slip casting, grouting mode after having some strength Be it is bottom-up, every section of slip casting length is slip casting step pitch, and opening length of steel pipe is slip casting step pitch length.Slip casting step pitch is generally selected 0.6~1m is taken, influence of the stratum inhomogeneity to slip casting effect can be effectively reduced in this way.During slip casting, every section of slip casting After the completion, the core pipe length an of step pitch, general value 60cm are moved up；

(7) using lifting means movement, or core pipe is symmetrically manually clamped using 2 pipe wrench, two sides are uniformly exerted oneself simultaneously, Core pipe is mobile.Every completion 3~4m slip casting length, will dismantle a section slip casting core pipe.After slip casting, in Grouting Pipe upper flap Upper boring cover, in order to the construction of multiple note.

(8) after tube drawing, the grouting of each single hole, Grouting Pipe should first be lifted to 60 centimetres, mud jacking again after staying a minute.Finally Before tube drawing, bulb valve in Grouting Pipe should be closed, Grouting Pipe is then extracted while slip casting.

Preferred embodiment is the dual slurry slip casting method, specifically includes the following steps:

Injected hole is laid: utilizing sleeve valve barrel grouting hole；

Mechanical equipment: ZMB-6 type hydraulic double-liquid grouting pump, slush pump；

Grouting Pipe: Φ 51mm in Grouting Pipe, resistance to compression 35Mpa；

Slurries: using cement and waterglass as host agent；

Down tube: lower 51 slip casting steel pipe of Φ, the bottom end of Grouting Pipe are protruded within solution cavity in hole, and Grouting Pipe uses floral tube, tube head Floral tube segment length is 2m；

Grout injection control: carrying out packer permeability test before slip casting, presses water pressure to be gradually increased to predetermined grouting pressure by small, and hold Continuous 15min；Just start formal dual slurry slip casting after packer permeability test is qualified；Slip casting carries out complete opening filling using two-shot grouting system Slurry, it is a small amount of to be in the milk repeatedly, repeatedly；The material used is general silicon P.0.42.5 cement slurry, water, glass pulp, and proportion is rule of thumb Temporary value are as follows: the ratio of mud 0.8；Cement slurry waterglass volume ratio is 1: 0.5；Cement: water: waterglass: the weight ratio of slip casting agent is 1000Kg:800Kg:700Kg:50Kg；Modulus of water glass 2.4~3.4,22~40 ° of Baume degrees；Grouting pressure control 0.3~ The range of 1MPa；Injection speed is 15~20L/min, and infiltration minimum diameter is set to 3.0m；

When slip casting, speed and the end time for determining slip casting are analyzed by the PQ instrument on grouting pump, intrusion is according to infiltration Radius consolidates volume to calculate；

Slip casting ending standard: when lasting when slip casting ending standard includes final midge amount and reaches predetermined design pressure Between；

Grouting Pipe blocks: after the completion of all hole-bottom slurry-injections, Grouting Pipe is no longer extracted, and is embedded in stratum；Grouting Pipe uses The pvc pipe of diameter 20mm caliber carries out slip casting packing to slip casting steel；Pressure is 0.3~1Mpa；During packing, one side slip casting Pvc pipe is promoted on one side, is promoted speed and is controlled according to field condition.

Preferred embodiment is the steel pillar follow-up, specifically:

It is bad for coating geology, the loose stake position of soil property, by the way of lengthening aperture casing to rock stratum top surface into Row processing；

When steel pile casting docks, interface should be used and is fully welded；

Outer casing is first buried before pile foundation construction, outer casing diameter should be 30cm~50cm bigger than stake diameter, and long 5m is answered when embedded Notice that the deviation of casing position, pre-buried position deviation are not greater than 5cm；Using than normally being bored at the 10cm big drill bit of drill It proceeds at the predetermined lowered position of interior casing, using 25T truck crane, first by interior steel pile casting merogenesis sinking such as predetermined position, then carries out Impact holing；

In the work progress of sinking steel pile casting, crane must be steady, firmly plays at the top of steel pile casting and on casing top The plan-position in face is placed in the middle；Simultaneously using the verticality of the good each section casing connection of horizontal ruler strict control, it must not exceed construction rule The 1/200 of model requirement, makes every effort to steel pile casting and vertically buries.

Preferred embodiment is that the processing in the drilling includes cement, clay, slabstone filling method and plain concrete backfill method；

The cement, clay, slabstone filling method specifically:

When being drilled near the top of exsolution hole hole, using small stroke, gradually hole to be pushed up and is punctured, mud face is declined to a great extent in hole, When there is solution cavity suddenly in drilling process, slabstone, clay and water are supplemented rapidly, and backfill height exceeds solution cavity top opening height not Less than 1m, then slabstone mixture to solution cavity side is added to form retaining wall outside clay rubble using small stroke ballistic clay；

It is transferred to after slabstone and clay are sufficiently formed in hole after retaining wall and spillage phenomenon all disappears and normally rushes in, after Continuous drilling extremely design stake bottom absolute altitude, pile foundation pore-forming；

There are still spillage phenomenons after backfill strike-on for the first time, can in mass ratio be cement: clay: slabstone

The ratio of=1:10:20 continues to backfill slabstone, clay, repeats the above process, until pile foundation pore-forming；

Backfilling material order of addition is cement, clay, slabstone；Continue to drill, if discovery mud mud loses seriously, then Overlapping investment slabstone and clay, are filled up until by solution cavity, guarantee that mud is non-leakage in hole；

Pile foundation pore-forming continues to creep into, until pile foundation pore-forming.It, can be according to piece when occurring spillage situation during drilling Stone: clay: the mass ratio of cement is that 20:10:1 ratio puts into slabstone, clay and cement；The plain concrete filling specifically:

For solution cavity height within the scope of 50~150 ㎝, molten chamber is when filling without filling or half, to be filled using plain concrete；When Low-grade concrete is inserted when drilling solution cavity spillage or when encountering inclined rock base, is impacted after separated in time using impact drill Pore-forming；

Concrete grade and match ratio, concrete grade generally use C20 plain concrete, add in concrete certain Early strength agent；

Placement method, for inclined rock base, to correct hole location, backfill plain concrete should with inclined rock base either flush, it is right At solution cavity, backfill top surface is higher than Upper Plate of Karst Cave 50cm；

Work points for attention: fill concrete intensity, which reaches 70% side, after backfill 8h to spud in again；

Continue to creep into, until pile foundation pore-forming；

When occurring spillage situation during drilling, reprocess according to the method described above.

Preferred embodiment is the list liquid cement slurry slip casting,

When using mini-valve tube single fluid grouting, for full packing solution cavity stake position, sent out according to the karst that pile foundation and injected hole disclose Situation is educated, uniformly distributed 4 holes along pile body periphery 20cm, all prospecting holes should all cement injection closing in time；Inlet well aperture Diametric requirements use 100mm, and vertical precision is less than 1.5%；

Mini-valve tube is made of Φ 90mm PVC outer tube, zinc-plated inner tube, rubber case, sealing ring etc., can only the slip casting to outside pipe, Slurry cannot be returned into pipe, pvc pipe bores one group every 50cm and penetrates slurry hole, and penetrating slurry hole tube bottom must seal；

Injecting paste material: slurries use single slurry, and single slurry injecting paste material uses P.O.32.5 grades of ordinary portland cements, The ratio of mud is 0.5:1~1:1；

Sheath body material formula, cement: silty clay: water=1:1.5:1.88,3d age compression strength are 0.3MPa.

Preferred embodiment is karst cave treatment during the concrete placings, specifically:

For mud norm controlling 1.2~1.3, the bulk density of concrete is 2.4t/m3 when formation of pile；

Mud off is intact before pouring, and mud off rupture or backfill object are squeezed and broken when pouring, and concrete, which is begun to flow into, to be split Gap or solution cavity, it is necessary to continue concrete perfusion, 3%~5% accelerator be added in the concrete of perfusion, at the beginning of controlling concrete The solidifying time, it is ensured that pile foundation being capable of one-time-concreting success.

After adopting the above technical scheme, the beneficial effects of the present invention are:

Due to karst region bridge solution cavity pile base construction method of the invention, comprising the following steps: punching and karst cave treatment, Punching and karst cave treatment are repeated, to the last pore-forming；Karst cave treatment, which specifically includes, identifies type and process method step, Wherein identify type be start drilling before, in drilling process and in filling process, according to vertical depth and whether there is or not fill out It fills object and judges type of cavern；Wherein processing method includes the pretreatment before construction, during the processing and concrete pouring in drilling Processing.The present invention is according to different geological conditions, the solution cavity pile foundation construction of different type of cavern, using different karst cave treatment sides Method keeps solution cavity pile foundation construction more safe and effective.Reach and accelerate pore-forming progress, guarantees pile quality, save the mesh of construction cost 's.

Detailed description of the invention

Fig. 1 is that pile foundation pours concrete chance rock crack schematic diagram；

Fig. 2 is that pile foundation pours concrete chance solution cavity schematic diagram；

Fig. 3 be pile foundation pour concrete rack backfill object schematic diagram；

Fig. 4 is solution cavity cement injection slurry hole arrangement schematic diagram；

Fig. 5 is according to vertical depth and the schematic diagram for having non-filler to judge type of cavern；

In figure: 1- pile body, 2- injected hole, before 3- is poured, when 4- is poured, after 5- is poured.

Specific embodiment

Understand to remove the objectives, technical solutions, and advantages of the present invention more, with reference to the accompanying drawings and embodiments, The present invention will be described in further detail.It should be appreciated that specific embodiment described herein is only used to explain this hair It is bright, it is not intended to limit the present invention.

It is common shown as shown in Figure 1 to Figure 4, a kind of karst region bridge solution cavity pile base construction method, comprising the following steps: punching And karst cave treatment, punching and karst cave treatment are repeated, to the last pore-forming；The present embodiment specifically includes: preparation of construction, side Case just selection, punching, karst cave treatment, continuing punching ..., (circulation carries out karst cave treatment, selects processing side according to actual effect Case, punching), pore-forming.

Karst cave treatment, specifically includes the following steps:

Identify type, start drilling before, in drilling process and in filling process, according to vertical depth and have Non-filler judges that type of cavern, type of cavern include that karst is generally developed, karst relatively development, karst pole is developed and full packing；

Processing method, processing method include the pretreatment before construction, the processing in drilling and the place during concrete pouring Reason；

Pre-process solution cavity develop for lava pole, in such a way that steel pillar follows up, karst generally develops, karst compared with Development and full packing solution cavity are based on cement injection, supplemented by dual slurry；

Processing in drilling is to backfill a certain proportion of slabstone, clay, cement, mass ratio 20:10:1；Concrete pouring Processing in the process is Concrete Filled.

In the present embodiment: karst cave treatment mode principle is as follows:

1) for the biggish stake position of solution cavity is had been found that in advance, pre-pouring grout processing is carried out according to solution cavity situation, the purpose is to subtract Less because the geological disasters such as collapse hole, landslide cause casualties.

2) since place is located at the high terrace in the Changjiang river, soluble scar directly covers cohesive soil etc., has no direct cover sand class The drilling of soil.Therefore, when subterrane is that when pressing from both sides conglomerate karst ground subsidence in construction work will not occur for calcareous sandstone；When When subterrane is limestone and karsts developing area, find out whether grey scar has a deep lapies, fluid bowl first, lapies top whether there is or not it is soft, Stream modeling shape admaic earth, such as finds above situation, then karst pole soil cave type surface collapse may occur, and Ying Jinhang pre-pouring grout is handled, Guarantee construction safety.

3) solution cavity without filling or half filling within vertical depth 3m, using backfill clay, rubble, slabstone or concrete Based on repeated stock wall building, the case where not found for prospecting and find solution cavity in pore forming process, equally uses slabstone, glues Soil, cement filled by a certain percentage, strike-on, until pore-forming if you need to repeatedly backfill strike-on can be properly added other additions Agent increases mud viscosity and colloidity, enhances mud off quality.

4) the case where in concreting process, such as finding solution cavity, liquid level decline occur or do not rise, using mixed Solidifying soil pours until pile.

5) it for shaped corroded cave model, is handled using pre-pouring grout and backfill slabstone and clay impact holing.It is configured in construction excellent Matter mud increases Slurry Storage amount, mortar leakage prevention collapse hole.

Identify the concrete mode of type are as follows:

Before starting drilling, base area surveys data and carries out rough estimates, and whether solution cavity is in beading point in the drilling of part Cloth determines solution cavity distribution, can also be according to sampling is surveyed in detail, and determination will spud in pier position with the presence or absence of solution cavity；According to closing on Construction pile foundation primarily determines construction area with the presence or absence of solution cavity；

In drilling process,

1. spillage: water level in borehole decline, cable wires at well head loosen extremely.

2. fishing for slag sample analysis: being analyzed according to slag specimen, see whether slag specimen anomalous variation occurs, occurred after such as entering rock The fillers situation such as clay.

3. drilling footage speed: in drilling process, drilling footage notes abnormalities before spillage, drilling depth more normal work It is fast when making, in fact it could happen that full packing bit deflection: to find that drill bit, wirerope deviate center in drilling process, primarily determine There is slope rock, small solution cavity or crack；In filling process, there is larger gap in concrete top surface lifting height and theoretical lifting height, It is determined as that concrete is lost, solution cavity occurs.

It is further comprising the steps of before construction: by the ground to solution cavity pile foundation of having constructed survey data, borehole log, at Hole time, the statistics and analysis that record, pile quality is perfused, to the solution cavity stake according to different geological conditions, different type of cavern Base construction, using different karst cave treatment methods, specifically:

It is bad for coating geology, the loose stake position of soil property, by the way of lengthening aperture casing to rock stratum roof plate into Row processing；When spillage occurring in hole, according to the filler of molten chamber, height, spillage speed different situations, backfill piece is respectively adopted The method of stone clay, concrete, bagged cement squeezes slabstone by small stroke, clay mixture forms more closely knit stable shield Wall；For large-scale single solution cavity and shaped corroded cave model, the processing mode to be followed up using full casing, steel pile casting is directly through molten Hole forms steel pile casting retaining wall.

According to vertical depth and there is non-filler to judge in type of cavern, specific judgment mode are as follows:

Karst is generally developed, h < 3, and no filling half is filled；

Karst is relatively developed, 3≤h≤5, no filling or half filling；

The development of karst pole, h > 5m, no filling or half filling；

Full packing；Solution cavity classification is detailed in Fig. 5.

Preprocess method in the present embodiment, based on cement injection, supplemented by dual slurry.

Karsts developing area situation at stake position is analyzed and determined in conjunction with installing intersection hole, determines that hole is deep to silt layer, alluvium, residual Lamination and basement rock boundary, and slip casting thickness only limits above-mentioned formation beds, other can be without pre-pouring grout.In an implementation with by Stake prospecting geological mapping be reported as criterion, for clearly have solution cavity in report stake position, quantity, selective preparatory progress Pre-pouring grout processing, to ensure construction safety.The work of cement slurry pressure injection starts to creep into again after completing 7 days.Pressure controls root when pressure injection It is determined according to on-site actual situations.

Is caused by hole wall collapse, drills it to prevent mud to be lost suddenly for the solution cavity of super-huge solution cavity or half filling Before, equally first take the method processing of high-pressure slip-casting filling, reinforcing.If finding that solution cavity is connection solution cavity in work progress, only It needs to carry out grouting and reinforcing to maximum solution cavity.

Grouting mode based on single fluid grouting, supplemented by dual slurry slip casting.In slip casting incipient stage and percolating water position Using two fluid grouting, percolating water crack and spillage gap are blocked, form one " only pulp layer ".

After dual slurry slip casting reaches water blockoff and caulking joint effect, then single slurry after-teeming slurry is carried out, further increases slurries and expand Range is dissipated, rock mass performance is improved.

Slip casting adjusts grouting mode and slip casting match ratio according to field condition.Dual slurry closure is carried out when spillage, reaches effect Single fluid grouting is carried out after fruit again and increases range of scatter.After single fluid grouting carries out a period of time, grouting pressure could not be promoted, can be again Secondary progress two fluid grouting processing, makes pressure reach design requirement.Two fluid grouting gelling time at this time is controlled in 3 minutes ranges, Conducive to slurries diffusion and constructing operation, the generation of pipeline plugging accident is reduced.

As shown in figure 4, single liquid cement slurry slip casting, when using mini-valve tube single fluid grouting, for full packing solution cavity stake position, root According to the karsts developing area situation that pile foundation and injected hole disclose, uniformly distributed 4 holes along 1 periphery 20cm of pile body, all prospecting holes should all and When cement injection close；Inlet well opening diameter requires to use 100mm, and vertical precision is less than 1.5%；Cement is using packed Normal silicate P.O.32.5 cement (dual slurry uses P.O.42.5 cement) is forbidden to go bad using expired, dampness, agglomeration Cement inferior；Water-cement ratio uses 0.27.After grout cures, solid body single shaft unconfined compressive strength should in 1.5MPa or more, Grouting pressure 0.3-1.0MPa；Shown in cloth hole Fig. 4 specific as follows.

Material requested and equipment injecting paste material: slurries use single slurry, and single slurry injecting paste material is general using P.O.32.5 grades Logical portland cement, the ratio of mud are 0.5:1~1:1.

Sleeve shell material: sleeve shell material basic function is the annulus closed between mini-valve tube and the wall of a borehole, slurry when preventing from being in the milk Liquid flees hither and thither, and under the cooperation of rubber sleeve valve and stop grouting plug, forcing slurries, only the open loop in a filling segment limit (racks set Shell material) and enter stratum.Low-intensity formula of the sleeve shell material based on cohesive soil, based on cement, participating in fine sand can be improved sleeve shell material Brittleness.This engineering uses for reference sheath body material formula, and cement: silty clay: water=1:1.5:1.88,3d age compression strength are 0.3MPa。

Pilot hole equipment: using HGY-100 type engineering geological drilling rig, takes out casing and drilling tool, follow-up after drilling Upper Plate of Karst Cave Using the Φ 90mm pvc pipe for meeting quality requirement.

Grouting equipment: ZMB-6 type hydraulic double-liquid grouting pump, and it is equipped with grouting pipeline system and pulping equipment slip casting.

Grouting Pipe: unidirectional mini-valve tube is used, mini-valve tube is by Φ 90mm PVC outer tube, zinc-plated inner tube, rubber case, sealing ring Deng composition, can only the slip casting to outside pipe, cannot return slurry into pipe, pvc pipe bores one group every 50cm and penetrates slurry hole, penetrate starch hole tube bottom must It must sealing.

Pretreatment is using single liquid cement slurry slip casting pretreatment, construction method are as follows:

(1) surveying and locating: according to the control point coordinates laid, the coordinate position of pilot hole is calculated, is put using total station Hole location out measures ground elevation with level, determines pilot hole depth；

(2) drilling, Completion of Drilling Hole method include that drilling machine is in place, drilling of sinking, propose drill bit, displacement four steps work, drilling machine peace After dress is in place, keep it steady, drill bit align piles hole location, drilling of sinking；When drilling, drilling machine keeps horizontal, guarantees the gradient of stake Less than design requirement value, drilling depth should reach grouting reinforcement section, to make a record in drilling process, provide for slip casting operation Reference data；

(3) it infuses sleeve shell material, be inserted into no eyelet steel pipe in the sky, and sleeve shell material is pressed by this pipe, until mud is complete in hole It is ejected outside hole entirely, extracts steel pipe；

(4) pipe laying, mini-valve tube connected according to pilot hole depth first, the mini-valve tube 20~30cm suitable for reading that bassets will connect Mouth is good with sharp underseal under good mini-valve tube；It then, will be in mini-valve tube tripping in hole, it is to be ensured that bottom hole, worst error are arrived under mini-valve tube No more than 20cm, be such as hampered power during assigning, and when cannot smoothly be inserted into, should ascertain the reason, and forbids strong using excessive external force Row indentation, water is filled into hole, protective cap is covered and makes marks after being installed；

(5) sealing, the ground around aperture to ground are once in the distance range of 1m using accelerated cement mortar envelope It is stifled, to prevent the generation of grout phenomenon during slip casting；

(6) slip casting, sleeve shell material conserve 3 days or so, use retrusive segmenting slip casting, grouting mode after having some strength Be it is bottom-up, every section of slip casting length is slip casting step pitch, and opening length of steel pipe is slip casting step pitch length.Slip casting step pitch is generally selected 0.6~1m is taken, influence of the stratum inhomogeneity to slip casting effect can be effectively reduced in this way.During slip casting, every section of slip casting After the completion, the core pipe length an of step pitch, general value 60cm are moved up；

(7) using lifting means movement, or core pipe is symmetrically manually clamped using 2 pipe wrench, two sides are uniformly exerted oneself simultaneously, Core pipe is mobile.Every completion 3~4m slip casting length, will dismantle a section slip casting core pipe.After slip casting, in Grouting Pipe upper flap Upper boring cover, in order to the construction of multiple note.

(8) after tube drawing, the grouting of each single hole, Grouting Pipe should first be lifted to 60 centimetres, mud jacking again after staying a minute.Finally Before tube drawing, bulb valve in Grouting Pipe should be closed, Grouting Pipe is then extracted while slip casting.

Slip casting ending standard: it uses cement grout slip casting: 1. meeting or exceeding design final pressure；2. amount < 100L/min eventually； 3. stable 20~30min of time.

8 hours start cleaning bottom of hole after infusing single liquid cement slurry, and universal experience is water filling after slip casting reaches ending standard After 15~30 minutes, orifice pressure gages is waited to naturally ring to pressure release after 1Mpa or less, starts the construction that cleaning bottom of hole carries out next step.

Pressure does not rise when for sleeve valve barrel grouting, liquid level does not increase or have when being lost channel using pressure dual slurry The method for blocking loss channel is handled, and is blocked and is continued to handle using mini-valve tube cement injection after being lost channel.

Dual slurry slip casting method, specifically includes the following steps:

Injected hole is laid: utilizing sleeve valve barrel grouting hole；

Mechanical equipment: ZMB-6 type hydraulic double-liquid grouting pump, slush pump；

Grouting Pipe: Φ 51mm in Grouting Pipe, resistance to compression 35Mpa；

Slurries: using cement and waterglass as host agent；The two is injected in a manner of biliquid according to a certain percentage, is added when necessary Injecting paste material composed by additives.It can reach fastly in the biggish stratum of groundwater velocity using the slurries of this mixed type The purpose of fast leak stopping；

Down tube: lower 51 slip casting steel pipe of Φ, the bottom end of Grouting Pipe are protruded within solution cavity in hole, and Grouting Pipe uses floral tube, tube head Floral tube segment length is 2m；Three groups are bored on steel pipe to perforation, use rubber for tire skin to wrap up in envelope outside hole, between Grouting Pipe and drilling Using cement slurry packing.

Grout injection control: carrying out packer permeability test before slip casting, presses water pressure to be gradually increased to predetermined grouting pressure by small, and hold Continuous 15min；Just start formal dual slurry slip casting after packer permeability test is qualified；Slip casting carries out complete opening filling using two-shot grouting system Slurry, it is a small amount of to be in the milk repeatedly, repeatedly；The material used is general silicon P.0.42.5 cement slurry, water, glass pulp, and proportion is rule of thumb Temporary value are as follows: the ratio of mud 0.8；Cement slurry waterglass volume ratio is 1: 0.5；Cement: water: waterglass: the weight ratio of slip casting agent is 1000Kg:800Kg:700Kg:50Kg；Modulus of water glass 2.4~3.4,22~40 ° of Baume degrees；Grouting pressure control 0.3~ The range of 1MPa；Injection speed is 15~20L/min, and infiltration minimum diameter is set to 3.0m；

When slip casting, speed and the end time for determining slip casting are analyzed by the PQ instrument on grouting pump, intrusion is according to infiltration Radius consolidates volume to calculate；Formula is, in formula, R is penetration radius；H is solution cavity height；μ be filler porosity, one As take 1%~5%；α is superfilled coefficient；λ be provincialism empirical coefficient, about 0.3~0.9, depending on nature of ground, γ, β For pack completeness and volumetric efficiency.These parameters and coefficient value can be determined according to field test.Slip casting uses high-pressure pump (pressure It can reach 2Mpa).

Slip casting ending standard: when lasting when slip casting ending standard includes final midge amount and reaches predetermined design pressure Between；General cement-waterglass biliquid ending standard is: grouting pressure reaches design final pressure；Midge amount is 50~100Lmin, Stablizing about 20min can terminate；Under normal conditions, level pressure slip casting is generally used, when grouting pressure reaches or approaches final pressure When terminate slip casting, when pressure is close to final pressure or reaches the 80% of final pressure, such as there is biggish running pulp, through interval slip casting logistics Portion, which reaches or approaches final pressure, can also terminate slip casting.

Mortar depositing construction points for attention: to prevent slurries loss is too far from causing to waste, using interval grouting mode, so that first The sand (or rubble) filled in the slurries and solution cavity of injection tentatively reaches slip casting again after gluing, and circulation slip casting is multiple, until reaching Until providing minimum grouting amount and grouting pressure controlling value.After having infused a hole, continue to carry out remaining hole slip casting, it is rear to infuse The pressure of slurry must be turned up, last sealing of hole.Grouting sequence is voluntarily grasped by scene.

Grouting Pipe blocks: after the completion of all hole-bottom slurry-injections, Grouting Pipe is no longer extracted, and is embedded in stratum；Grouting Pipe uses The pvc pipe of diameter 20mm caliber carries out slip casting packing to slip casting steel；Pressure is 0.3~1Mpa；During packing, one side slip casting Pvc pipe is promoted on one side, is promoted speed and is controlled according to field condition.

Infuse the pre- pipe-blocking-proof measure of dual slurry, the main feature of cement-water-clay system first is that gelling time is fast (general Control is within the scope of 60s~180s), it is injected using biliquid mode, the more single liquid of construction technology is complicated.The above characteristic is be easy to cause The generation of pipeline plugging accident in slip casting batch process.Pipeline plugging accident is a great problem of (cement-sodium silicate) dual slurry construction.For Reduce the generation of pipeline plugging accident, it should be noted that the following in dual slurry work progress:

1. the installation of grout pipe line should shorten the length of slurries convergence tube as far as possible, the length of slurries convergence tube should be controlled 1 Within rice；The threeway mixer of cement-water-clay system meet should install pressure reducing valve, and can be filled the water and be cleared up by pressure reducing valve Converge pipeline；

2. two fluid grouting should deactivate waterglass before temporarily stopping, slip casting 60 seconds to 120 seconds again in a manner of single liquid cement slurry, The biliquid mixed serum in grouting pipeline is displaced with neat slurry, prevents the blocking of grout pipe line；

3. can adjust dual slurry match ratio after water blockoff, leak stopping success, extending the dual slurry presetting period；

4. sufficiently carrying out the preparation before dual slurry slip casting, reduces slip casting and temporarily stop to infuse number and duration in the process.

The follow-up of steel pillar, specifically:

It is bad for coating geology, the loose stake position of soil property, by the way of lengthening aperture casing to rock stratum top surface into Row processing；Quick spillage after breakdown solution cavity is prevented, hole wall loses mud off pressure support and cause to cave in.Take such scheme After processing, alleviate dependence of the overburden layer to mud off, though occur spillage, hole wall will not because of overburden layer unstability and It collapses.It avoids backfilling repeatedly, causes artificial, material, machinery and the increase of duration, reach smoothly by the requirement in final hole.

When steel pile casting docks, interface should be used and is fully welded；The increase with casing submergence depth is avoided, the pressure born Power is continuously increased, and causes the fracture of casing, and upper and lower two sections casing is detached from deviation.

Outer casing is first buried before pile foundation construction, outer casing diameter should be 30cm~50cm bigger than stake diameter, and long 5m is answered when embedded Notice that the deviation of casing position, pre-buried position deviation are not greater than 5cm；Using than normally being bored at the 10cm big drill bit of drill It proceeds at the predetermined lowered position of interior casing, using 25T truck crane, first by interior steel pile casting merogenesis sinking such as predetermined position, then carries out Impact holing；

In the work progress of sinking steel pile casting, crane must be steady, firmly plays at the top of steel pile casting and on casing top The plan-position in face is placed in the middle；Simultaneously using the verticality of the good each section casing connection of horizontal ruler strict control, it must not exceed construction rule The 1/200 of model requirement, makes every effort to steel pile casting and vertically buries.If once discovery has the tendency that deflection, corrected at once, it would be possible to The unfavorable factor glanced off is eliminated in budding state.

Processing in drilling includes cement, clay, slabstone filling method and plain concrete backfill method；

Cement, clay, slabstone filling method specifically:

When being drilled near the top of exsolution hole hole, using small stroke, gradually hole is pushed up and is punctured, prevent card from hammering into shape, once discovery hole Interior mud face is declined to a great extent, and when there is solution cavity suddenly in drilling process, supplements slabstone, clay and water rapidly, backfill height is super Solution cavity top opening height is not less than 1m out, and slabstone size 30-50cm is advisable, and slabstone, clay 2:1 in mass ratio are launched, and supplements simultaneously Water, it is ensured that collapse hole, slabstone backfill height are not less than 1m beyond solution cavity top opening height, are then rushed using using small stroke in hole Hitting clay adds slabstone mixture to solution cavity side to form retaining wall outside clay rubble；

It is transferred to after slabstone and clay are sufficiently formed in hole after retaining wall and spillage phenomenon all disappears and normally rushes in, after Continuous drilling extremely design stake bottom absolute altitude, pile foundation pore-forming；

There are still spillage phenomenons after backfill strike-on for the first time, can in mass ratio be cement: clay: slabstone

The ratio of=1:10:20 continues to backfill slabstone, clay, repeats the above process, until pile foundation pore-forming；

Backfilling material order of addition is cement, clay, slabstone；Continue to drill, if discovery mud mud loses seriously, then Overlapping investment slabstone and clay, are filled up until by solution cavity, guarantee that mud is non-leakage in hole；

Pile foundation pore-forming continues to creep into, until pile foundation pore-forming.It, can be according to piece when occurring spillage situation during drilling Stone: clay: the mass ratio of cement is that 20:10:1 ratio puts into slabstone, clay and cement；

Plain concrete filling specifically:

For solution cavity height within the scope of 50~150 ㎝, molten chamber is when filling without filling or half, to be filled using plain concrete；When Low-grade concrete is inserted when drilling solution cavity spillage or when encountering inclined rock base, is impacted after separated in time using impact drill Pore-forming；

Concrete grade and match ratio, concrete grade generally use C20 plain concrete, add in concrete certain Early strength agent；To improve concrete strength as early as possible, the construction time is saved, certain early strength agent should be added in concrete, is improved The early strength of plain concrete.

Construction precautions: fill concrete intensity, which reaches 70% side, after backfill 8h to spud in again.

Placement method, for inclined rock base, to correct hole location, backfill plain concrete should with inclined rock base either flush, it is right At solution cavity, backfill top surface is higher than Upper Plate of Karst Cave 50cm；

Construction precautions: fill concrete intensity, which reaches 70% side, after backfill 8h to spud in again；

Continue to creep into, until pile foundation pore-forming；

When occurring spillage situation during drilling, reprocess according to the method described above.

Data is surveyed there is no solution cavity for base area but the stake that mud face declines suddenly occurs in normal drill process, is adopted Take same method；To small-sized or multilayer karst cave, there is calabash shaped for pass after preventing it from not altering hole or pore-forming with adjacent holes, it must Low grade concrete can be perfused when wanting to be filled, crept into again after waiting by force.

Karst cave treatment during concrete placings, specifically:

For mud norm controlling 1.2~1.3, the bulk density of concrete is 2.4t/m3 when formation of pile；Concrete and mud (or water) bulk density difference is larger, when hole wall nearby has rock crack or solution cavity, during filling concrete not due to bulk density Together, the difference of the pressure generated will lead to mud off rupture, and concrete flows into crack or solution cavity.

As shown in Figure 1, Figure 2 and Figure 3, it is intact to pour preceding 3 mud off, the rupture of 4 mud offs or backfill object quilt when pouring It racks, concrete begins to flow into crack or solution cavity, it is necessary to continue concrete perfusion, be added 3%~5% in the concrete of perfusion Accelerator, control the concrete initial set time, it is ensured that pile foundation can one-time-concreting success；5 be after pouring in figure.

Using karst region bridge solution cavity pile base construction method of the invention, acquirement is had the beneficial effect that:

Reasonable processing scheme is selected according to the type of solution cavity with the above karst cave treatment method, accelerates pile foundation work The construction speed of journey；Ensure pile foundation engineering hole quality and construction safety simultaneously, the solution cavity pile foundation constructed is examined through ultrasonic wave Instrument detection is surveyed, pile foundation engineering is superior in quality, is I class stake；And be conducive to solution cavity pile foundation engineering cost control.

Performance analysis during solution cavity pile foundation construction, according to the classification of solution cavity, selects economically viable processing scheme, leads to It crosses and accelerates construction progress, control the construction cost of solution cavity pile foundation engineering, reduce mechanical one-shift and meter labour cost.According to scene Practice of construction situation statistics, selects reasonable processing scheme, and every solution cavity pile foundation can be made to shift to an earlier date 3-5 completion constructions, corresponding to save About cost be 3480-5800 yuan (800 yuan/machine-team × 3 day of mechanical one-shift+dataller, 120 yuan × 3 people × 3 day=3480 yuan, 800 yuan/machine-team × 5 day of mechanical one-shift+120 × 3 people × 5 day=5800 yuan of dataller).Every solution cavity pile foundation is cost-saved 3480 yuan to 5800 yuan, statistics are surveyed in base area has 220 or so solution cavity pile foundations that need to carry out specially treated, from economy at For this, according to solution cavity size, fills situation and select economically viable processing technique scheme, it is contemplated that is cost-saved 76.56 ten thousand yuan to 127.6 ten thousand yuan.

Application effect, although this engineering has been carried out ground geological mapping, due to bore position, the limitation of quantity, and The geological condition of underground complexity cannot be verified completely, and some of complex geological form has Unpredictability, do not pay attention to slightly in construction It will result in serious quality, safety accident and economic loss, therefore in the main construction techniques of analysis Pile In Karst Area On the basis of, start with from Pile In Karst Area whole process quality control and summarize the technical controlling measure of its construction, suchly to the later period Pile foundation construction quality, progress and cost control under the conditions of matter are of great significance.

The preferred embodiment of present invention described above, is not intended to limit the invention, it is all in spirit of the invention and Made any modification within principle, etc. same karst region bridge solution cavity pile base construction method and paving method structure change Into etc., it should all be included in the protection scope of the present invention.

Claims (10)

1. karst region bridge solution cavity pile base construction method, which comprises the following steps: punching and karst cave treatment repeat Punching and karst cave treatment are executed, to the last pore-forming；

The karst cave treatment, specifically includes the following steps:

Identify type, start drilling before, in drilling process and in filling process, according to vertical depth and whether there is or not fillings Object judges that type of cavern, type of cavern include that karst is generally developed, karst relatively development, karst pole is developed and full packing；

Processing method the treating method comprises the pretreatment before constructing, the processing in drilling and the processing during concrete pouring；

Described to pre-process the solution cavity developed for lava pole, by the way of the follow-up of steel pillar, karst is generally developed, karst is relatively sent out It educates with full packing solution cavity based on cement injection, supplemented by dual slurry；

Processing in the drilling is to backfill a certain proportion of slabstone, clay, cement, mass ratio 20:10:1；

Processing during the concrete pouring is Concrete Filled.

2. bridge solution cavity pile base construction method in karst region according to claim 1, which is characterized in that the identification type Concrete mode are as follows:

Before starting drilling, base area surveys data and carries out rough estimates, and whether solution cavity is in moniliform distribution in the drilling of part, determines Solution cavity distribution, can also be according to sampling be surveyed in detail, and determination will spud in pier position with the presence or absence of solution cavity；According to closing on construction stake Base primarily determines construction area with the presence or absence of solution cavity；

In drilling process, if water level in borehole decline, cable wires at well head loosen extremely, show spillage situation occur；According to slag specimen It is analyzed, sees whether slag specimen anomalous variation occurs；Judged according to penetration rate, in drilling process, is crept into before spillage Drilling depth notes abnormalities, fast when drilling depth is compared with normal operation in normal, in fact it could happen that full packing；According to drill bit, whether deflection is judged, It finds that drill bit, wirerope deviate center in drilling process, primarily determines slope rock, small solution cavity or crack occur；

In filling process, there is larger gap in concrete top surface lifting height and theoretical lifting height, are determined as that concrete is lost, occur Solution cavity.

3. bridge solution cavity pile base construction method in karst region according to claim 1, which is characterized in that also wrapped before construction It includes following steps: data, borehole log, pore-forming time, perfusion record, pile quality is surveyed by the ground to solution cavity pile foundation of having constructed Statistics and analysis, to the solution cavity pile foundation construction according to different geological conditions, different type of cavern, using different karst cave treatments Method, specifically:

It is bad for coating geology, the loose stake position of soil property, by the way of lengthening aperture casing to rock stratum roof plate Reason；When spillage occurring in hole, according to the filler of molten chamber, height, spillage speed different situations, it is viscous that backfill slabstone is respectively adopted The method of soil, concrete, bagged cement squeezes slabstone by small stroke, clay mixture forms more closely knit stable retaining wall；

For large-scale single solution cavity and shaped corroded cave model, the processing mode to be followed up using full casing, steel pile casting is directly through molten Hole forms steel pile casting retaining wall.

4. bridge solution cavity pile base construction method in karst region according to claim 1, which is characterized in that the basis is vertically deep It spends and there is non-filler to judge in type of cavern, specific judgment mode are as follows:

Karst is generally developed, h < 3, and no filling half is filled；

Karst is relatively developed, 3≤h≤5, no filling or half filling；

The development of karst pole, h > 5m, no filling or half filling；

Full packing.

5. bridge solution cavity pile base construction method in karst region according to claim 1, which is characterized in that the pretreatment uses Single liquid cement slurry slip casting pretreatment, construction method are as follows:

(1) surveying and locating: according to the control point coordinates laid, the coordinate position of pilot hole is calculated, uses total station bleed hole Position measures ground elevation with level, determines pilot hole depth；

(2) drilling, Completion of Drilling Hole method include that drilling machine is in place, drilling of sinking, propose that drill bit, displacement four steps work, drilling machine are installed just Behind position, keep it steady, drill bit align piles hole location, drilling of sinking；When drilling, drilling machine keeps horizontal, guarantees that the gradient of stake is less than Design requirement value, drilling depth should reach grouting reinforcement section, to make a record in drilling process, provide reference number for slip casting operation According to；

(3) it infuses sleeve shell material, be inserted into no eyelet steel pipe in the sky, and sleeve shell material is pressed by this pipe, until mud quilt completely in hole It ejects outside hole, extracts steel pipe；

(4) pipe laying, first according to pilot hole depth connect mini-valve tube, the mini-valve tube 20~30cm suitable for reading that bassets, by what is connected Mouth is good with sharp underseal under mini-valve tube；It then, will be in mini-valve tube tripping in hole, it is to be ensured that bottom hole is arrived under mini-valve tube, worst error does not surpass 20cm is crossed, be such as hampered power during assigning, and when cannot smoothly be inserted into, should ascertain the reason, and forbids to press by force using excessive external force Enter, fill water after being installed into hole, cover protective cap and makes marks；

(5) sealing, the ground around aperture to ground is once in the distance range of 1m using the closure of accelerated cement mortar, to prevent Only during slip casting grout phenomenon generation；

(6) slip casting, sleeve shell material conserve 3 days or so, use retrusive segmenting slip casting after having some strength, grouting mode is under Upwards, every section of slip casting length is slip casting step pitch, and opening length of steel pipe is slip casting step pitch length, slip casting step pitch generally chooses 0.6 ~ Influence of the stratum inhomogeneity to slip casting effect can be effectively reduced in 1m in this way, during slip casting, after the completion of every section of slip casting, Move up the core pipe length an of step pitch, general value 60cm；

(7) using lifting means movement, or core pipe is symmetrically manually clamped using 2 pipe wrench, two sides are uniformly exerted oneself simultaneously, by core pipe Mobile, every completion 3~4m slip casting length, will dismantle a section slip casting core pipe, after slip casting, the boring cover in Grouting Pipe upper flap, In order to the construction of multiple note；

(8) after tube drawing, the grouting of each single hole, Grouting Pipe should first be lifted to 60 centimetres, mud jacking again after staying a minute, last tube drawing Before, bulb valve in Grouting Pipe should be closed, Grouting Pipe is then extracted while slip casting.

6. bridge solution cavity pile base construction method in karst region according to claim 1, which is characterized in that the dual slurry slip casting Method, specifically includes the following steps:

Injected hole is laid: utilizing sleeve valve barrel grouting hole；

Mechanical equipment: ZMB-6 type hydraulic double-liquid grouting pump, slush pump；

Grouting Pipe: Φ 51mm in Grouting Pipe, resistance to compression 35Mpa；

Slurries: using cement and waterglass as host agent；

Down tube: lower 51 slip casting steel pipe of Φ, the bottom end of Grouting Pipe are protruded within solution cavity in hole, and Grouting Pipe uses floral tube, tube head floral tube Segment length is 2m；

Grout injection control: packer permeability test is carried out before slip casting, pressure water pressure is gradually increased to predetermined grouting pressure by small, and continues 15min；Just start formal dual slurry slip casting after packer permeability test is qualified；Slip casting carries out complete opening grouting using two-shot grouting system, It is a small amount of to be in the milk repeatedly, repeatedly；For general silicon, P.0.42.5 cement slurry, water, glass pulp, proportion rule of thumb temporarily take the material used Value are as follows: the ratio of mud 0.8；Cement slurry waterglass volume ratio is 1: 0.5；Cement: water: waterglass: the weight ratio of slip casting agent is 1000Kg:800Kg:700Kg:50Kg；Modulus of water glass 2.4~3.4,22~40 ° of Baume degrees；Grouting pressure control 0.3~ The range of 1MPa；Injection speed is 15~20L/min, and infiltration minimum diameter is set to 3.0m；

When slip casting, analyze speed and the end time for determining slip casting by PQ instrument on grouting pump, intrusion according to penetration radius, Volume is consolidated to calculate；

Slip casting ending standard: duration when slip casting ending standard includes final midge amount and reaches predetermined design pressure；

Grouting Pipe blocks: after the completion of all hole-bottom slurry-injections, Grouting Pipe is no longer extracted, and is embedded in stratum；Grouting Pipe uses diameter The pvc pipe of 20mm caliber carries out slip casting packing to slip casting steel；Pressure is 0.3~1 Mpa；During packing. while slip casting Pvc pipe is promoted, speed is promoted and controls according to field condition.

7. bridge solution cavity pile base construction method in karst region according to claim 1, which is characterized in that the steel pillar with Into, specifically:

It is bad for coating geology, the loose stake position of soil property, by the way of lengthening aperture casing to rock stratum top surface Reason；

When steel pile casting docks, interface should be used and is fully welded；

Outer casing is first buried before pile foundation construction, outer casing diameter should be 30cm~50cm bigger than stake diameter, and long 5m should be noted that shield when embedded The deviation of cylinder position, pre-buried position deviation are not greater than 5cm；Using than normally creeping at the 10cm big drill bit of drill to interior shield At the predetermined lowered position of cylinder, using 25T truck crane, first by interior steel pile casting merogenesis sinking such as predetermined position, then impact holing is carried out；

In the work progress of sinking steel pile casting, crane must be steady, firmly plays at the top of steel pile casting and in casing top surface Plan-position is placed in the middle；Simultaneously using the verticality of the good each section casing connection of horizontal ruler strict control, it must not exceed job specfication and want 1/200 asked makes every effort to steel pile casting and vertically buries.

8. bridge solution cavity pile base construction method in karst region according to claim 1, which is characterized in that the place in the drilling Reason includes that cement, clay, slabstone filling method and plain concrete backfill method；

The cement, clay, slabstone filling method specifically:

When being drilled near the top of exsolution hole hole, using small stroke, gradually hole is pushed up and is punctured, mud face is declined to a great extent in hole, works as brill Into slabstone, clay and water when occurring solution cavity suddenly in the process, is supplemented rapidly, backfill height is not less than beyond solution cavity top opening height Then 1m adds slabstone mixture to solution cavity side to form retaining wall outside clay rubble using small stroke ballistic clay；

It is transferred to after slabstone and clay are sufficiently formed in hole after retaining wall and spillage phenomenon all disappears and normally rushes in, continue to creep into To design stake bottom absolute altitude, pile foundation pore-forming；

When for the first time backfill strike-on after there are still spillage phenomenons, can in mass ratio be cement: clay: slabstone=1:10:20 ratio after Continuous backfill slabstone, clay, repeat the above process, until pile foundation pore-forming；

Backfilling material order of addition is cement, clay, slabstone；Continue to drill, if discovery mud mud loses seriously, repeats throwing Enter slabstone and clay, filled up until by solution cavity, guarantees that mud is non-leakage in hole；

Pile foundation pore-forming continues to creep into, until pile foundation pore-forming can be according to slabstone when occurring spillage situation during drilling: glutinous Soil: the mass ratio of cement is that 20:10:1 ratio puts into slabstone, clay and cement；

The plain concrete filling specifically:

For solution cavity height within the scope of 50~150 ㎝, molten chamber is when filling without filling or half, to be filled using plain concrete；When drilling Low-grade concrete is inserted when solution cavity spillage or when encountering inclined rock base, uses impact drill impact holing after separated in time；

Concrete grade and match ratio, concrete grade generally use C20 plain concrete, and it is strong that certain morning is added in concrete Agent；

Placement method, for inclined rock base, to correct hole location, backfill plain concrete should with inclined rock base either flush, for molten At hole, backfill top surface is higher than Upper Plate of Karst Cave 50cm；

Construction precautions: fill concrete intensity, which reaches 70% side, after backfill 8h to spud in again；

Continue to creep into, until pile foundation pore-forming；

When occurring spillage situation during drilling, reprocess according to the method described above.

9. bridge solution cavity pile base construction method in karst region according to claim 5, which is characterized in that the list liquid cement slurry Slip casting,

When using mini-valve tube single fluid grouting, for full packing solution cavity stake position, the karsts developing area feelings disclosed according to pile foundation and injected hole Condition, uniformly distributed 4 holes along pile body periphery 20cm, all prospecting holes should all cement injection closings in time；Inlet well opening diameter It is required that using 100mm, vertical precision is less than 1.5%；

Mini-valve tube is made of Φ 90mm PVC outer tube, zinc-plated inner tube, rubber case, sealing ring etc., can only the slip casting to outside pipe, Bu Nengxiang Slurry is returned in pipe, pvc pipe bores one group every 50cm and penetrates slurry hole, and penetrating slurry hole tube bottom must seal；

Injecting paste material: slurries use single slurry, and single slurry injecting paste material uses P.O.32.5 grades of ordinary portland cements, the ratio of mud For 0.5:1~1:1；

Sheath body material formula, cement: silty clay: water=1:1.5:1.88,3d age compression strength are 0.3MPa.

10. bridge solution cavity pile base construction method in karst region according to claim 1, which is characterized in that the concrete placings mistake Karst cave treatment in journey, specifically:

For mud norm controlling 1.2~1.3, the bulk density of concrete is 2.4t/m3 when formation of pile；

Mud off is intact before pouring, and mud off rupture or backfill object are squeezed and broken when pouring, concrete begin to flow into crack or Solution cavity, it is necessary to continue concrete perfusion, 3%~5% accelerator is added in the concrete of perfusion, controls the concrete initial set time, Ensure that pile foundation being capable of one-time-concreting success.