CN112982360A - Construction method for treating soft soil roadbed by vacuum combined loading preloading method - Google Patents
Construction method for treating soft soil roadbed by vacuum combined loading preloading method Download PDFInfo
- Publication number
- CN112982360A CN112982360A CN202110284028.2A CN202110284028A CN112982360A CN 112982360 A CN112982360 A CN 112982360A CN 202110284028 A CN202110284028 A CN 202110284028A CN 112982360 A CN112982360 A CN 112982360A
- Authority
- CN
- China
- Prior art keywords
- construction
- vacuum
- layer
- sealing
- laying
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 238000010276 construction Methods 0.000 title claims abstract description 64
- 239000002689 soil Substances 0.000 title claims abstract description 41
- 238000011068 load Methods 0.000 title claims abstract description 29
- 238000007789 sealing Methods 0.000 claims abstract description 57
- 239000004576 sand Substances 0.000 claims abstract description 34
- 238000003756 stirring Methods 0.000 claims abstract description 34
- 239000002002 slurry Substances 0.000 claims abstract description 32
- 239000004746 geotextile Substances 0.000 claims abstract description 26
- 238000005086 pumping Methods 0.000 claims abstract description 18
- 239000004033 plastic Substances 0.000 claims abstract description 13
- 229920003023 plastic Polymers 0.000 claims abstract description 13
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 10
- 210000003371 Toes Anatomy 0.000 claims description 9
- 238000006073 displacement reaction Methods 0.000 claims description 9
- 238000005507 spraying Methods 0.000 claims description 8
- 229910000831 Steel Inorganic materials 0.000 claims description 7
- 239000004927 clay Substances 0.000 claims description 7
- 229910052570 clay Inorganic materials 0.000 claims description 7
- 238000005056 compaction Methods 0.000 claims description 7
- 230000003203 everyday Effects 0.000 claims description 7
- 239000000463 material Substances 0.000 claims description 7
- 239000010959 steel Substances 0.000 claims description 7
- 229920000915 polyvinyl chloride Polymers 0.000 claims description 6
- 239000004800 polyvinyl chloride Substances 0.000 claims description 6
- 238000010009 beating Methods 0.000 claims description 5
- 235000017166 Bambusa arundinacea Nutrition 0.000 claims description 4
- 235000017491 Bambusa tulda Nutrition 0.000 claims description 4
- 235000008733 Citrus aurantifolia Nutrition 0.000 claims description 4
- 235000015334 Phyllostachys viridis Nutrition 0.000 claims description 4
- 235000015450 Tilia cordata Nutrition 0.000 claims description 4
- 235000011941 Tilia x europaea Nutrition 0.000 claims description 4
- 239000011425 bamboo Substances 0.000 claims description 4
- 239000004571 lime Substances 0.000 claims description 4
- 239000002184 metal Substances 0.000 claims description 4
- 239000002245 particle Substances 0.000 claims description 4
- 238000005096 rolling process Methods 0.000 claims description 4
- 239000004677 Nylon Substances 0.000 claims description 3
- 230000036975 Permeability coefficient Effects 0.000 claims description 3
- 230000005484 gravity Effects 0.000 claims description 3
- 238000009434 installation Methods 0.000 claims description 3
- 229920001778 nylon Polymers 0.000 claims description 3
- 238000000926 separation method Methods 0.000 claims description 3
- 238000011105 stabilization Methods 0.000 claims description 3
- IVBHGBMCVLDMKU-GXNBUGAJSA-N Piperacillin Chemical compound O=C1C(=O)N(CC)CCN1C(=O)N[C@H](C=1C=CC=CC=1)C(=O)N[C@@H]1C(=O)N2[C@@H](C(O)=O)C(C)(C)S[C@@H]21 IVBHGBMCVLDMKU-GXNBUGAJSA-N 0.000 claims description 2
- 238000004458 analytical method Methods 0.000 claims description 2
- 238000009412 basement excavation Methods 0.000 claims description 2
- 238000005553 drilling Methods 0.000 claims description 2
- 239000000203 mixture Substances 0.000 claims description 2
- 230000035699 permeability Effects 0.000 claims description 2
- 238000004062 sedimentation Methods 0.000 claims description 2
- 240000003917 Bambusa tulda Species 0.000 claims 1
- 238000004080 punching Methods 0.000 abstract description 3
- 238000009435 building construction Methods 0.000 abstract description 2
- 239000012528 membrane Substances 0.000 description 9
- 238000000034 method Methods 0.000 description 9
- 230000000694 effects Effects 0.000 description 4
- 241001330002 Bambuseae Species 0.000 description 3
- 238000011049 filling Methods 0.000 description 3
- 230000037250 Clearance Effects 0.000 description 2
- 210000001503 Joints Anatomy 0.000 description 2
- 238000004140 cleaning Methods 0.000 description 2
- 230000035512 clearance Effects 0.000 description 2
- 239000000945 filler Substances 0.000 description 2
- 238000002955 isolation Methods 0.000 description 2
- 230000001681 protective Effects 0.000 description 2
- 229910001335 Galvanized steel Inorganic materials 0.000 description 1
- 239000004567 concrete Substances 0.000 description 1
- 238000005520 cutting process Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000007599 discharging Methods 0.000 description 1
- 238000000605 extraction Methods 0.000 description 1
- 239000008397 galvanized steel Substances 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000006011 modification reaction Methods 0.000 description 1
- 239000004745 nonwoven fabric Substances 0.000 description 1
- 239000011150 reinforced concrete Substances 0.000 description 1
- 239000010802 sludge Substances 0.000 description 1
- 238000003892 spreading Methods 0.000 description 1
- 230000003068 static Effects 0.000 description 1
- 230000032258 transport Effects 0.000 description 1
- 238000004804 winding Methods 0.000 description 1
Classifications
-
- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D3/00—Improving or preserving soil or rock, e.g. preserving permafrost soil
-
- E—FIXED CONSTRUCTIONS
- E01—CONSTRUCTION OF ROADS, RAILWAYS, OR BRIDGES
- E01C—CONSTRUCTION OF, OR SURFACES FOR, ROADS, SPORTS GROUNDS, OR THE LIKE; MACHINES OR AUXILIARY TOOLS FOR CONSTRUCTION OR REPAIR
- E01C3/00—Foundations for pavings
-
- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D19/00—Keeping dry foundation sites or other areas in the ground
- E02D19/06—Restraining of underground water
- E02D19/12—Restraining of underground water by damming or interrupting the passage of underground water
- E02D19/18—Restraining of underground water by damming or interrupting the passage of underground water by making use of sealing aprons, e.g. diaphragms made from bituminous or clay material
-
- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D3/00—Improving or preserving soil or rock, e.g. preserving permafrost soil
- E02D3/02—Improving by compacting
- E02D3/10—Improving by compacting by watering, draining, de-aerating or blasting, e.g. by installing sand or wick drains
Abstract
The invention relates to a construction method for treating a soft soil roadbed by a vacuum combined loading preloading method, which belongs to the field of building construction and comprises the steps of clearing a foundation and backfilling and leveling; slurry stirring the sealed wall; laying a medium coarse sand cushion layer; inserting and punching a plastic drainage plate; burying a monitoring and detecting instrument; constructing a sealing ditch; burying a vacuum pipeline and installing vacuum pumping equipment; laying a layer of geotextile; laying three layers of sealing films in layers; vacuumizing; laying a layer of geotextile; a fine sand cushion layer; carrying out graded stacking to full load elevation; and unloading to the design elevation. The vacuum combined surcharge preloading method is applied to the construction of the soft soil roadbed, the drainage consolidation speed of the soft soil roadbed is accelerated, the post-construction settlement is reduced, the stability of the roadbed in the construction is ensured, the roadbed construction is obviously accelerated, the construction period is greatly shortened, the safety is improved, and the construction quality is improved.
Description
Technical Field
The invention relates to a construction method, in particular to a construction method for treating a soft soil roadbed by a vacuum combined preloading method, and belongs to the field of building construction.
Background
The foundation of partial areas in China is a soft soil roadbed mainly comprising soft clay and sludge, the soft soil roadbed is not easy to process, the phenomenon of differential settlement after construction is serious, and the manufacturing cost is correspondingly increased, so that the processing of the soft soil roadbed has great influence on the engineering quality and the construction period.
Disclosure of Invention
The invention aims to solve the technical problem of providing a construction method for treating a soft soil roadbed by a vacuum combined preloading method.
In order to solve the above problems, the specific technical scheme of the invention is as follows: the construction method for treating the soft soil roadbed by the vacuum combined loading preloading method comprises the following steps: clearing foundation of a site, backfilling and leveling;
step two: mud stirring sealing wall
1) Measuring and paying off;
2) arranging a stirring unit, wherein the pile position alignment error is not more than 50mm, leveling the stirring machine after the pile position alignment error is in place, keeping the horizontal of the mechanical disc bottom and the vertical of a guide frame, enabling the guide frame and a stirring shaft to be vertical to the ground, and enabling the verticality deviation to be not more than 1%;
3) preparing slurry, wherein the slurry is prepared by adding water into clay, the permeability coefficient of the stirring pile wall is less than 1 multiplied by 10 < -5 > cm/s, the slurry doping ratio is more than 35 percent, and the specific gravity is more than 1.35;
4) pouring the slurry into a collecting hopper;
5) stirring and feeding the slurry, statically spraying for 20-30s after the stirring head sinks to the required depth, and lifting the stirring head while spraying the slurry after the slurry and the pile end soil are fully stirred;
6) moving the next pile position, and repeating the steps until the construction of the area is completed;
step three: paving medium coarse sand cushion
The mud content in the medium and coarse sand cushion layer is not more than 5%, the maximum particle diameter is not more than 50mm, and the laying thickness is 50 cm;
step four: inserting-beating plastic drainage plate
The material is selected from an SPB100-C type plastic drainage plate;
step five: monitoring and detecting instrument is buried underground
1) The settlement plates are buried in the road center, the road shoulder and the base of the toe;
2) the displacement observation side piles are buried in toe portions on two sides of the embankment and 10m away from the outer edge and the outer edge of the side ditch, measuring points are distributed in the section positions of the predicted possible slip crack surface and the ground in combination with stability analysis, and 3-4 displacement side piles are arranged away from the toe portions;
3) laying an inclinometer pipe and a layered settling pipe, wherein the inclinometer pipe and the layered settling pipe enter a hard soil layer for at least 3 m;
step six: construction of sealing trench
Excavating a sealing ditch, wherein the top width of the sealing ditch is 1.4m, the bottom width is 0.5m, the ditch depth is 1.5m, 10cm is reserved, manual excavation and leveling are adopted, three layers of sealing films and geotextiles are laid after construction is completed, and cohesive soil is backfilled, wherein the backfilling height is 20-30cm away from the original ground;
step seven: vacuum pipeline and vacuum pumping equipment installation are buried underground
The filter tubes are made of PVC tubes, small holes with the hole diameter of 8-10 mm are drilled in the tube walls at intervals of 50cm to form flower tubes, nylon yarns are wound outside the flower tubes, a layer of non-woven geotextile is wrapped to serve as a sand separation layer, and the two filter tubes are connected through steel wire rubber tubes; the filter tubes are arranged in a lattice shape at intervals of 6 m;
step eight: laying a layer of geotextile
The geotextiles are overlapped, and the overlapping width is not less than 20 cm;
step nine: laying three layers of sealing films in layers
1) The vacuumizing sealing film is paved by adopting two layers of polyvinyl chloride films, and the thickness of the films is 0.12 mm;
2) the same 1) constructing and laying a second layer of sealing film and a third layer of sealing film, burying sealing ditches at two sides of the sealing films, backfilling clay sealing ditches, and tamping in layers;
step ten: vacuum pumping
Adopting a jet type vacuum pump, wherein the single machine power is not less than 7.5kW, and the post-pumping vacuum pressure is not less than-96 kPa;
step eleven: laying a layer of geotextile
After the tenth step, laying a layer of non-woven geotextile on the sealing film when the vacuum pressure under the sealing film reaches 80 kPa;
step twelve: fine sand cushion
Laying a 50cm thick fine sand cushion layer on the geotextile to be used as sand of the vacuum combined loading cushion layer, wherein the fine sand with higher water permeability is adopted, and the mud content is not more than 5%;
step thirteen: grading stacking to full load elevation
After the vacuum pumping and the pressure stabilization reach 80kPa, a first-stage load is added, sandy soil selected by a stacking material is filled, a road roller is adopted for rolling, the cross slope is strictly controlled to be 2 percent, the side slope is controlled to be 1:1.5, the settlement amount is not more than 25mm every day, the horizontal displacement does not exceed 5mm every day, the loading is stopped when the settlement rate exceeds, and after the settlement amount is stabilized, the earthwork is continuously filled until the loading height is reached.
Fourteen steps: unloading to design elevation
And after the vacuum preloading constant load meets the design requirement, unloading, leveling the ground by a bulldozer to the design standard, excavating the slurry stirring wall for 1.5m, and tamping with medium coarse sand until the compaction degree reaches 93%.
In the first step, plain soil is backfilled to a designed leveling elevation layer by layer according to 3% of cross slopes on both sides or 2% of one side, the thickness of the layer after compaction is not more than 30cm, and the degree of compaction is 85%.
In the fourth step, a measurer discharges axial positions of a horizontal direction and a vertical direction according to a plane layout drawing, the horizontal direction is 10m in one, the left, the middle and the right are three points, the longitudinal direction is 20m in one, the position of a drainage plate is discharged by adopting a steel ruler according to the axial positions, marks are made by using bamboo sticks, lime is spread, the distance between the drainage plates is 1 multiplied by 1m, and the drainage plates are arranged in a square shape; and moving the plate inserting machine for positioning, and installing the drainage plate pile shoe.
According to the metal movable vertical needle and the dial which are arranged on the board inserting machine, the verticality deviation when the pile pipe is inserted downwards is controlled not to be larger than +/-1.5%, and the landing positioning error of the pile shoe of the board inserting machine is controlled within +/-50 mm during construction operation.
The construction of the plate inserting machine adopts a method of punching a plastic drainage plate in a sleeve type, the length of the drainage plate is recorded after the drainage plate reaches the designed depth, the drainage plate is cut, and the exposed length is controlled to be 20 cm.
In the fifth step, the side piles are buried on the same horizontal axis, the length of the side piles is not less than 1.5m, the cross section of each side pile can be square or circular, the buried depth of the side piles is greater than 1.2m, and the height of the pile top exposed out of the ground is not more than 10 cm.
The invention has the following beneficial effects: the vacuum combined preloading method is adopted, the vacuum degree and the preloading material double-layer preloading are utilized, the advantages of the vacuum degree and the preloading material double-layer preloading are well utilized, the superposition effect is generated in a combined mode, the foundation settlement can be accelerated, the preloading quality is improved, the preloading time is shortened, and the construction period is shortened.
The construction mode that the flexible isolation and the rigid isolation are combined to optimize the sealing ditch and the load is applied in a grading manner during construction is adopted, so that the influence of vacuum pressure on surrounding buildings in the construction process is reduced, and the safety is improved.
By adopting the extension type plate inserting machine, structures with clearance limitation are distributed along the reconstruction and extension construction position, the problem of clearance limitation is solved, and the construction operation safety is improved.
The vacuum combined preloading method does not need large equipment, has strong practicability to the ultra-soft foundation or the region close to the dangerous slope, which is difficult to apply load, reduces the entrance and exit of the large equipment, reduces the construction cost and improves the safety of operators.
The vacuum combined preloading method has the advantages of low construction noise, increased effect of loading earthwork, small interference to the surrounding environment, simple operation, economy and safety.
Drawings
Fig. 1 is a schematic flow chart of a construction method for treating a soft soil roadbed by a vacuum combined loading and preloading method.
Detailed Description
The vacuum combined surcharge preloading is to continuously vacuumize the soft soil foundation under the closed membrane, causing the air pressure in the membrane to reduce, when the pressure difference between the air inside and outside the membrane reaches a certain value, making the water in the soil in the gap produce seepage, and then the water is discharged outside the membrane through the drainage system, the pressure of the water in the gap is continuously reduced, the soil body is continuously compacted, the effective force is continuously increased, when the pressure difference tends to zero, the seepage stops, and the consolidation is completed. During the process of vacuumizing, the preloading is carried out, the effective force is increased, the sedimentation is accelerated, and the consolidation time is shortened.
The construction process is shown in figure 1, the foundation is cleaned and backfilled and leveled
1. Dredging and backfilling a pond and a ditch: firstly, draining water in a pond or a ditch, removing silt in the pond or the ditch, excavating ridges at intervals among the ponds, and transporting to a specified spoil point; after dredging, the coarse sand in the road bed is backfilled layer by layer, and a temporary construction drainage ditch is made to prevent the roadbed from being soaked by the accumulated water.
2. And when the soil is in a common soil area, removing the surface soil with the thickness of 0.3m, and then performing leveling layer construction.
3. Backfilling with plain soil according to 3% of cross slope on both sides or 2% of single side to designed leveling height, controlling thickness of layering not more than 30cm after compacting, and compacting degree of 85%.
Mud stirring sealing wall
1. And (4) measuring and paying off, performing construction lofting on the pile positions according to drawing requirements by a measurer according to control points, marking each pile position, and compiling a pile number so as to check and recheck in time.
2. And arranging a stirring unit, positioning the pile driver, and ensuring that the pile position is accurate and the pile position centering error is not more than 50 mm. After the mixer is in place, the mixer is leveled, the level of the mechanical disc bottom is kept to be vertical to the guide frame, the guide frame and the mixer shaft must be vertical to the ground, and the deviation of the verticality is not more than 1%.
3. The slurry is prepared by adding water into clay, the permeability coefficient of the stirring pile wall is required to be less than 1 multiplied by 10 < -5 > cm/s, and the slurry doping ratio is more than 35 percent and the specific gravity is more than 1.35.
4. And (3) stirring the slurry according to a predetermined mixing ratio, and continuously stirring the slurry in a stirrer until the slurry is fed. And pouring the slurry into a collecting hopper before delivering the slurry. The slurry after stirring is sieved, and the prepared slurry cannot be isolated.
5. Stirring and slurry feeding are carried out on the stirring pile by adopting a four-stirring two-spraying process, after a stirring head sinks to the designed depth, static spraying is carried out for 20-30s, and after the slurry and pile end soil are fully stirred, the stirring head is lifted, and slurry spraying is carried out at the same time. The slurry pumping must be continuous, the sinking is strictly controlled according to the design, and the lifting speed is less than or equal to 0.8 m/min.
6. And repeatedly sinking and lifting the guniting and stirring to achieve the effects of four stirring and two spraying.
7. And moving the next pile position, and repeating the steps until the construction of the area is completed.
Paving medium coarse sand cushion
Laying a sand cushion layer, wherein the mud content is not more than 5%, and the maximum particle diameter is not more than 50 mm; after the site is leveled, discharging a construction sideline and scattering a lime line; calculating according to the sand volume transported by each vehicle, drawing a square grid, drawing filling elevations by adopting bamboo poles, controlling the spacing within 10m, properly increasing the control elevation according to the field width, and ensuring that the thickness of a sand cushion layer in a construction site meets the design requirement by adopting a double control standard; the dump truck transports the sand to the construction site and unloads according to the square grid. And leveling by a bulldozer, wherein the paving thickness is 50 cm.
Inserting-beating plastic drainage plate
1. The driving depth of the plastic drainage plate material determined according to the thickness of a soft soil layer (silt layer) of field geological survey is 25-35 m, and an SPB100-C type plastic drainage plate is selected; .
2. Measuring and lofting, releasing the positions of transverse and longitudinal releasing axes, wherein the transverse direction is 10m in one, the left, middle and right points are three, the longitudinal direction is 20m in one, releasing the position of a drainage plate by using a steel ruler, marking by using a bamboo stick, spreading lime, and arranging the drainage plates in a square shape with the distance of 1 multiplied by 1 m.
3. And moving the plate inserting machine for positioning, and installing the drainage plate pile shoe. According to the metal movable vertical needle and the dial which are arranged on the plate inserting machine, the verticality deviation when the pile pipe is inserted downwards is controlled not to be larger than +/-1.5%. During construction operation, the landing positioning error of the pile shoe of the board inserting machine is controlled within the range of +/-50 mm.
4. The construction of the plate inserting machine adopts a method of driving a plastic drainage plate in a sleeve type, the speed of pulling up and down the pile pipe is controlled, the speed is not too high, and the length of the drainage plate is recorded after the drainage plate reaches the designed depth. And (4) checking whether the phenomenon of the returning belt exists after the construction of the drainage plate is finished, and if the length of the returning belt exceeds 60cm, additionally punching a strip at a position 20cm away from the plate position.
5. And cutting the drainage plate, and controlling the exposed length to be 20 cm.
6. And moving the setter to the next plate position.
7. In the construction process of the drainage plate, a specially-assigned person needs to be sent to make a construction original record. After the construction of the plastic drainage plate is completed, the drainage plate head in the area is cleaned in time for finishing work, and then self-checking is carried out.
Monitoring and detecting instrument is buried underground
1. The settlement plate is buried in the road center, the road shoulder and the base of the toe. The settlement plate consists of a reinforced concrete bottom plate, a metal measuring rod and a protective sleeve. The bottom plate is not less than 50cm multiplied by 3cm as far as possible, the diameter of the measuring rod is 4cm, and the protective sleeve is preferably sized to be capable of sleeving the measuring rod and enabling the scale to enter the sleeve. Along with the increase of the filled soil, the measuring rod and the sleeve are also connected to be high, and the length of each section is not more than 50 cm. The measuring rod top surface after the height connection is slightly higher than the sleeve upper opening, the sleeve upper opening is covered with a cover to seal the pipe opening, the influence of filler falling into the pipe on the measuring rod sinking freedom degree is avoided, and the height of the cover top higher than the rolling surface is not suitable to be larger than 50 cm. In the construction process, reliable protection measures are taken for the settlement plate, and the settlement plate is not deformed and damaged.
2. The displacement observation side piles are buried in the toe parts of both sides of the embankment and 10m away from the outer edge and the outer edge of the side ditch, and 3-4 displacement side piles are arranged outside the toe parts. Side piles of the same observation section are buried on the same transverse axis; the side pile is a timber pile with the length not less than 1.5m, the section can be square or round, and the side length or the diameter is preferably 15 cm; a measuring head which is not easy to wear is arranged on the pile top; the depth of the side piles is preferably not less than 1.2m below the ground surface, and the height of the pile tops exposed out of the ground is not more than 10 cm. The embedding adopts a driving method, 50cm of the upper part of the periphery of the pile is fixed by pouring concrete, and the side pile is ensured to be stably embedded.
3. Laying an inclinometer pipe and a layered settling pipe, wherein the length of the pipe is required to be at least 3m when entering a hard soil layer.
Construction of sealing trench
1. The sealing ditch is excavated according to the position of the sealing wall, the top width of the sealing ditch is 1.4m, the bottom width of the sealing ditch is 0.5m, and the ditch depth is 1.5 m. And reserving 10cm, and manually excavating and leveling.
2. And after the construction of the three layers of sealing films and geotextiles is finished, backfilling cohesive soil in the sealing ditch, and tamping by using a small-sized tamping machine when backfilling, wherein the tamping thickness is not more than 25 cm.
3. The backfill height is 20-30cm from the bottom of the original ground, and the backfill structure can serve as a drainage ditch during vacuumizing.
Vacuum pipeline and vacuum-pumping equipment for installation
The filter tube is a 75mm diameter PVC tube, the wall thickness is 3.5-4.0 mm, and the compressive strength is 100 kPa; drilling small holes with the aperture of 8-10 mm at intervals of 50cm on the pipe wall to prepare a flower pipe, winding nylon yarns outside the flower pipe, and then wrapping a layer of 200 g/square meter non-woven geotextile as a sand separation layer, wherein the non-woven fabric wrapping the filter pipe is not damaged and is tightly wrapped; the two filter pipes are connected by a steel wire rubber pipe.
The filter tubes are arranged in a lattice shape at intervals of 6 m. According to the size of the design requirement of each prepressing area, arranging and connecting the filter pipes, adopting steel wire rubber hoses at joints, fastening and fastening the joints by using hoops, then paving a film-paving elevation base surface beside a pipeline, digging a filter pipe ditch, burying the pipe while digging the ditch, filling the ditch with medium and coarse sand, and enabling the pipe top to be coated with the sand with the thickness of 20 cm. The film outlet position is connected with the joint by adopting a seamless galvanized steel pipe, and the film surface is vertically extended by 30 cm.
Laying a layer of geotextile
And paving by adopting a manual paving mode. The geotextiles are overlapped, and the overlapping width is not less than 20 cm. The geotextile is smoothly straightened when being paved, is tightly attached to the lower bearing layer, extends outwards for 1m around the reinforced area and is fixed by a sand bag or a mud bag.
The geotextile mainly plays a role in protecting the sealing membrane in the vacuumizing process and preventing the pipeline and the drainage plate from bursting or puncturing the sealing membrane under the vacuum pressure.
Laying three layers of sealing films in layers
1. The vacuum-pumping sealing film adopts two layers of polyvinyl chloride films, and the thickness of the films is 0.12 mm.
2. And constructing and laying a second layer of sealing film and a third layer of sealing film in the same steps. Burying sealing ditches at two sides of the sealing film, backfilling clay sealing ditches after the width of the laid sealing film is qualified, compacting in layers, and checking and accepting the compaction degree according to the roadbed structure standard.
3. The phenomenon of no sealing caused by laying of the sealing film is avoided. After the laying is finished, the sealing film is pressed by sand bags around the sealing film to prevent the sealing film from being blown away by wind.
Vacuum pumping
And a jet flow type vacuum pump is adopted, the single machine power is not less than 7.5kW, and the vacuum pressure after pumping is not lower than-96 kPa.
1. Trial vacuum
And adjusting the initial readings of various instruments, starting the pump to pump, simultaneously checking the operation condition of each pump and the sealing condition of the film, timely processing the problems, and ensuring that the real pressure under the film reaches 60-80 KPa in the vacuum trying stage.
2. Formal air extraction
In the formal air exhaust process, the vacuum degree in the film is maintained to be more than 80kPa during the vacuum exhaust.
And controlling the vacuum pumping speed during vacuum pumping, gradually increasing the number of the working pumps, checking whether the air leakage phenomenon exists or not, and performing repairing work. The vacuum pump can be started 1/3 within 1-2 days after the air is extracted, then the vacuum pump is started gradually according to the speed of 2 pumps/day, the vacuum degree reaches 80kPa for 5-7 days, and after the pressure is stabilized for 3-5 days, a fine sand cushion layer is laid. The effective time of vacuumizing is estimated to be 90 days. The starting number of the vacuum-pumping equipment at the later stage of construction exceeds 80 percent of the total number.
Laying a layer of geotextile
And laying a layer of non-woven geotextile on the sealing membrane when the vacuum pressure under the membrane reaches 80 kPa.
Fine sand cushion
Laying a 50cm thick fine sand cushion layer on the geotextile to be used as sand of the vacuum combined loading cushion layer, wherein the mud content is not more than 5%. The sand cushion layer is laid by manpower or small-sized machinery. The method is mainly used for preventing the roadbed filler particles from bursting or puncturing the lower geotextile and the sealing membrane during the layered and graded roadbed filling construction at the next stage.
Grading stacking to full load elevation
The combined stacking is performed according to a loading planning diagram and loading rate control indexes, the vacuum pumping and pressure stabilization are performed to reach 80kPa, the first-stage load is added, sandy soil selected by a stacking material is filled, a road roller is adopted for rolling, the cross slope is strictly controlled to be 2%, the slope is controlled to be 1:1.5, the good drainage state in a field is kept, the compactness meets the design requirement, the settlement rate is monitored and observed according to measurement every day, the settlement amount is not more than 25mm every day, the horizontal displacement is not more than 5mm every day, if the settlement rate is exceeded, the loading is stopped, after the settlement amount is stable, the earth is filled continuously until the loading height is reached.
Unloading to design elevation
And when the vacuum preloading constant load meets the design requirement, unloading, and leveling the ground to the design standard by adopting equipment such as a bulldozer and the like. The slurry stirring wall is excavated to 1.5m and is tamped by medium coarse sand, and the compactness requirement of the slurry stirring wall reaches 93 percent.
What has been described above is merely a preferred embodiment of the invention. It will be understood by those skilled in the art that various changes and modifications may be made without departing from the principles of the invention and these are intended to be included within the scope of the invention.
Claims (6)
1. A construction method for treating a soft soil roadbed by a vacuum combined loading preloading method is characterized by comprising the following steps: the method comprises the following steps: clearing foundation of a site, backfilling and leveling;
step two: mud stirring sealing wall
1) Measuring and paying off;
2) arranging a stirring unit, wherein the pile position alignment error is not more than 50mm, leveling the stirring machine after the pile position alignment error is in place, keeping the horizontal of the mechanical disc bottom and the vertical of a guide frame, enabling the guide frame and a stirring shaft to be vertical to the ground, and enabling the verticality deviation to be not more than 1%;
3) preparing slurry, wherein the slurry is prepared by adding water into clay, the permeability coefficient of the stirring pile wall is less than 1 multiplied by 10 < -5 > cm/s, the slurry doping ratio is more than 35 percent, and the specific gravity is more than 1.35;
4) pouring the slurry into a collecting hopper;
5) stirring and feeding the slurry, statically spraying for 20-30s after the stirring head sinks to the required depth, and lifting the stirring head while spraying the slurry after the slurry and the pile end soil are fully stirred;
6) moving the next pile position, and repeating the steps until the construction of the area is completed;
step three: paving medium coarse sand cushion
The mud content in the medium and coarse sand cushion layer is not more than 5%, the maximum particle diameter is not more than 50mm, and the laying thickness is 50 cm;
step four: inserting-beating plastic drainage plate
The drilling depth of the plastic drainage plate is within the range of 25-35 m, and an SPB100-C type plastic drainage plate is selected;
step five: monitoring and detecting instrument is buried underground
1) The settlement plates are buried in the road center, the road shoulder and the base of the toe;
2) the displacement observation side piles are buried in toe portions on two sides of the embankment and within 10m from the outer edge of the side ditch to the outer edge, measuring points are distributed at the section positions of the predicted possible slip crack surface and the ground in combination with stability analysis, and 3-4 displacement side piles are arranged outside the toe portions;
3) laying an inclinometer pipe and a layered settling pipe, wherein the inclinometer pipe and the layered settling pipe enter a hard soil layer for at least 3 m;
step six: construction of sealing trench
Excavating a sealing ditch, wherein the top width of the sealing ditch is 1.4m, the bottom width is 0.5m, the ditch depth is 1.5m, 10cm is reserved, manual excavation and leveling are adopted, three layers of sealing films and geotextiles are laid after construction is completed, and cohesive soil is backfilled, wherein the backfilling height is 20-30cm away from the original ground;
step seven: vacuum pipeline and vacuum pumping equipment installation are buried underground
The filter tubes are made of PVC tubes, small holes with the hole diameter of 8-10 mm are drilled in the tube walls at intervals of 50cm to form flower tubes, nylon yarns are wound outside the flower tubes, a layer of non-woven geotextile is wrapped to serve as a sand separation layer, and the two filter tubes are connected through steel wire rubber tubes; the filter tubes are arranged in a lattice shape at intervals of 6 m;
step eight: laying a layer of geotextile
The geotextiles are overlapped, and the overlapping width is not less than 30 cm;
step nine: laying three layers of sealing films in layers
1) The vacuumizing sealing film is paved by adopting two layers of polyvinyl chloride films, and the thickness of the films is 0.12 mm;
2) the same 1) constructing and laying a second layer of sealing film and a third layer of sealing film, burying sealing ditches at two sides of the sealing films, backfilling clay sealing ditches, and tamping in layers;
step ten: vacuum pumping
Adopting a jet type vacuum pump, wherein the single machine power is not less than 7.5kW, and the post-pumping vacuum pressure is not less than-96 kPa;
step eleven: laying a layer of geotextile
After the tenth step, when the vacuum pressure under the sealing film reaches 80kPa, paving a layer of non-woven geotextile on the sealing film;
step twelve: fine sand cushion
Laying a 50cm thick silty sand cushion layer on the geotextile to serve as a vacuum combined surcharge preloading cushion layer, wherein silty sand with high water permeability is adopted, and the mud content is not more than 5%;
step thirteen: grading stacking to full load elevation
After the vacuum pumping and the pressure stabilization reach 80kPa, a first-stage load is added, sandy soil selected by a stacking material is filled, a road roller is adopted for rolling, the cross slope is strictly controlled to be 2 percent, the side slope is controlled to be 1:1.5, the settlement amount is not more than 25mm every day, the horizontal displacement does not exceed 5mm every day, the loading is stopped when the settlement rate exceeds, and after the settlement amount is stabilized, the stacking earthwork is continuously filled until the design loading height is reached.
Fourteen steps: unloading to design elevation
When the vacuum preloading constant load meets the design requirement and the sedimentation amount is less than 5 mm/month for two months continuously, unloading is started, the field is leveled to the design standard by adopting a bulldozer, the slurry stirring wall is excavated by 1.5m and is tamped by medium-coarse sand, and the compaction degree reaches 93 percent.
2. The construction method for treating the soft soil roadbed by the vacuum combined preloading method according to claim 1, wherein the construction method comprises the following steps: in the first step, plain soil is backfilled to a designed leveling elevation layer by layer according to 3% of cross slopes on both sides or 2% of one side, the thickness of the layer after compaction is not more than 30cm, and the degree of compaction is 85%.
3. The construction method for treating the soft soil roadbed by the vacuum combined preloading method according to claim 1, wherein the construction method comprises the following steps: in the fourth step, a measurer discharges horizontal and vertical discharge axis positions according to a plane layout, every 10m is taken as a cross section in the horizontal direction, three points including a left point, a middle point and a right point are arranged in the same cross section, every 20m points are longitudinally arranged, the positions of the drainage plates are discharged by adopting a steel ruler according to the axis positions and marked by bamboo sticks, lime is spread, the distance between the drainage plates is 1 multiplied by 1m, and the drainage plates are arranged in a square shape; and moving the plate inserting machine for positioning, and installing the drainage plate pile shoe.
4. The construction method for treating the soft soil roadbed by the vacuum combined preloading method according to claim 3, wherein the construction method comprises the following steps: according to the metal movable vertical needle and the dial which are arranged on the board inserting machine, the verticality deviation when the pile pipe is inserted downwards is controlled not to be larger than +/-1.5%, and the landing positioning error of the pile shoe of the board inserting machine is controlled within +/-50 mm during construction operation.
5. The construction method for treating the soft soil roadbed by the vacuum combined preloading method according to claim 3, wherein the construction method comprises the following steps: the method is characterized in that a sleeve type beating method is adopted for beating the plastic drainage plate during the construction of the plate inserting machine, the length of the drainage plate is recorded after the drainage plate reaches the designed depth, the drainage plate is cut, and the exposed length is controlled to be 20 cm.
6. The construction method for treating the soft soil roadbed by the vacuum combined preloading method according to claim 1, wherein the construction method comprises the following steps: and fifthly, the side piles in the same section are buried on the same horizontal axis, the length of the side piles is not less than 1.5m, the section can be square or circular, the burying depth of the side piles is more than 1.2m, and the height of the pile tops exposed out of the ground is not more than 10 cm.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110284028.2A CN112982360A (en) | 2021-03-17 | 2021-03-17 | Construction method for treating soft soil roadbed by vacuum combined loading preloading method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110284028.2A CN112982360A (en) | 2021-03-17 | 2021-03-17 | Construction method for treating soft soil roadbed by vacuum combined loading preloading method |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN112982360A true CN112982360A (en) | 2021-06-18 |
Family
ID=76334048
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202110284028.2A Pending CN112982360A (en) | 2021-03-17 | 2021-03-17 | Construction method for treating soft soil roadbed by vacuum combined loading preloading method |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN112982360A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114215040A (en) * | 2021-12-28 | 2022-03-22 | 中铁二局集团有限公司 | Vacuum preloading construction method for coastal soft foundation |
| CN114215039A (en) * | 2021-12-28 | 2022-03-22 | 中铁二局集团有限公司 | Vacuum preloading construction method for coastal soft foundation treatment |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2009070984A1 (en) * | 2007-11-02 | 2009-06-11 | Yonggen Liang | Vacuum preloading method without drain sand cushion layer |
| CN203755293U (en) * | 2014-01-27 | 2014-08-06 | 中铁二十二局集团第一工程有限公司 | Vacuum preloading combined stacking system |
| CN110747840A (en) * | 2019-10-25 | 2020-02-04 | 中交四航局广州南沙工程有限公司 | Vacuum combined surcharge-load prepressing soft foundation reinforcing construction method |
| CN210104706U (en) * | 2019-04-16 | 2020-02-21 | 华弘建设集团有限公司 | Construction structure for treating deep and thick soft foundation by vacuum combined preloading |
| CN112411518A (en) * | 2020-12-17 | 2021-02-26 | 中交三公局第三工程有限公司 | Soft foundation section vacuum combined surcharge preloading construction method |
-
2021
- 2021-03-17 CN CN202110284028.2A patent/CN112982360A/en active Pending
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2009070984A1 (en) * | 2007-11-02 | 2009-06-11 | Yonggen Liang | Vacuum preloading method without drain sand cushion layer |
| CN203755293U (en) * | 2014-01-27 | 2014-08-06 | 中铁二十二局集团第一工程有限公司 | Vacuum preloading combined stacking system |
| CN210104706U (en) * | 2019-04-16 | 2020-02-21 | 华弘建设集团有限公司 | Construction structure for treating deep and thick soft foundation by vacuum combined preloading |
| CN110747840A (en) * | 2019-10-25 | 2020-02-04 | 中交四航局广州南沙工程有限公司 | Vacuum combined surcharge-load prepressing soft foundation reinforcing construction method |
| CN112411518A (en) * | 2020-12-17 | 2021-02-26 | 中交三公局第三工程有限公司 | Soft foundation section vacuum combined surcharge preloading construction method |
Non-Patent Citations (1)
| Title |
|---|
| 丰培洁主编；王占锋，吴潮玮副主编: "《建筑地基基础》", 31 January 2018, 北京理工大学出版社 * |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114215040A (en) * | 2021-12-28 | 2022-03-22 | 中铁二局集团有限公司 | Vacuum preloading construction method for coastal soft foundation |
| CN114215039A (en) * | 2021-12-28 | 2022-03-22 | 中铁二局集团有限公司 | Vacuum preloading construction method for coastal soft foundation treatment |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN210104706U (en) | Construction structure for treating deep and thick soft foundation by vacuum combined preloading | |
| CN106703050A (en) | Expansive soil road cutting side slope reinforced soil back-pressure seepage-preventive supporting structure and construction method thereof | |
| CN112982360A (en) | Construction method for treating soft soil roadbed by vacuum combined loading preloading method | |
| CN104264680B (en) | The method for processing foundation of Tian Wa joint portion, a kind of collapsible loess slope | |
| CN106759473A (en) | The constructing structure and its construction method of underground pipe gallery and road | |
| CN107151950A (en) | The construction method of desert area railway underground water route moat | |
| CN112281857A (en) | Deep foundation pit excavation construction method | |
| CN110593375A (en) | Pipe burying construction method for pipeline by adopting digging groove | |
| CN111677095A (en) | Construction method of drainage pipeline | |
| CN112411518A (en) | Soft foundation section vacuum combined surcharge preloading construction method | |
| CN107724401A (en) | The construction method of bridge pier foundation ditch | |
| CN111560958A (en) | Construction method of water-rich deep foundation pit in silty clay stratum | |
| CN112695763A (en) | Deep sludge stratum foundation pit excavation method | |
| CN112064751A (en) | Deep groove construction method for drainage pipeline | |
| CN101591906A (en) | The method for processing foundation of intubate, multipass vacuum well-point dewatering dynamic consolidation | |
| CN111608174A (en) | Karst area karst cave treatment method based on punched cast-in-place pile | |
| CN206220108U (en) | Cut Slopes of Expansive Soil reinforced earth back-pressure antiseepage supporting construction | |
| CN107724499A (en) | The construction method and pedestal of sewage conduct | |
| CN211421169U (en) | Fill side slope gravity type retaining wall reinforced structure | |
| CN111042144B (en) | Excavation method for foundation pit of underground beam under condition of continuous flow of riverway in cold region | |
| CN109083100B (en) | River channel excavation construction process after mud blowing and landing | |
| CN109235474B (en) | Structure of super-large cofferdam based on marine environment and construction process thereof | |
| CN111501729A (en) | Vacuum preloading drainage consolidation method for silt titanium dioxide tailings | |
| CN111472359A (en) | Method for replacing and filling peat soil soft foundation box culvert foundation | |
| CN110820719A (en) | Vacuum preloading dynamic compaction electroosmosis method for conductive plastic drainage plate |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| RJ01 | Rejection of invention patent application after publication |
Application publication date: 20210618 |