CN112049103A - Construction method for rapid drainage and reinforcement of soft soil foundation - Google Patents
Construction method for rapid drainage and reinforcement of soft soil foundation Download PDFInfo
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- CN112049103A CN112049103A CN202010961302.0A CN202010961302A CN112049103A CN 112049103 A CN112049103 A CN 112049103A CN 202010961302 A CN202010961302 A CN 202010961302A CN 112049103 A CN112049103 A CN 112049103A
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- 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
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- 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 quickly draining and reinforcing a soft soil foundation, belonging to the technical field of geotechnical engineering and constructional engineering and aiming at solving the specific technical problem of how to quickly reduce the water content in the soft soil body to enable the bearing capacity of the soft soil body to meet the use requirement of the foundation.
Description
Technical Field
The invention belongs to the technical field of geotechnical engineering and constructional engineering, and particularly relates to a construction method for quickly draining and reinforcing a soft soil foundation.
Background
The soft soil layer cannot be directly used as a natural foundation like other original foundations due to the engineering characteristics of high water content, high compressibility, low strength, weak permeability, long deformation time and the like of the soft soil layer, and the original physical characteristics of the foundation soil must be changed through technical measures to solve the problems of sedimentation and stability of the foundation and enable the bearing capacity of the soft soil layer to meet the use requirements. Drainage consolidation and reinforcement are effective ways for treating soft soil foundations, the drainage consolidation and reinforcement technology of soft soil foundations is generally adopted in the field of geotechnical engineering nowadays, the technology mainly adopts drainage measures to accelerate drainage consolidation of soft soil bodies, the water content of the soft soil bodies after drainage consolidation is reduced, the porosity is reduced, the bearing capacity is improved, and the use requirements of the foundations can be met. The main methods for consolidating soft soil by drainage consolidation at present are as follows: surface drainage method, sand cushion method, vacuum preloading method, and vacuum-preloading method.
In the patent of "a vertical layered water pumping soft soil rapid consolidation method and device" with publication number CN 105714761a, the rapid water drainage consolidation method is mainly connected with a magnetron and a vertical water drainage steel pipe through a vacuum pump, wherein a certain number of holes are distributed on the surface of the vertical water drainage steel pipe and placed in a soft soil foundation, and the method achieves the purpose of layered water drainage consolidation of the soft soil foundation by comprehensively adopting microwave heating and vacuum preloading technologies. The method has two defects, one is that when the underground water level of the soft soil foundation is not high, water in the soft soil foundation is mainly pore water, at the moment, the water is drained by adopting a vacuum pump for pumping water, the water pumping is only effective on soil bodies in a certain range around the vertical drainage pipe, the water pumping efficiency of the soil bodies at a certain distance away from the vertical drainage pipe is low, and the rapid drainage of the soft soil bodies cannot be guaranteed; secondly, the method has complex process system and high economic cost, and the requirements of quick drainage and consolidation of the soft soil foundation with a tight construction period cannot be met due to the fact that the equipment installation and water pumping time is long due to the limitation of construction conditions and personnel during field construction.
The patent of "a prepressing method and device for strong drainage method" published under the number CN 109056693a is obtained in the published literature, the drainage method is mainly to arrange a drainage plate body in the soft soil foundation, arrange a water collecting box and a jet pipe body at the lower part of the drainage plate body, drain the water in the soft soil body into the drainage plate through the water pressure difference between the drainage plate body and the surrounding soft soil body, and then drain the water in the jet pipe body out of the foundation range through a fluid conduit by high pressure fluid. The method mainly has two defects, one is that the water drainage method also needs high-pressure fluid as a water drainage power source, so that the economic consumption is high; secondly, the embedded jet pipe body and the fluid pipeline need larger earth excavation amount, and the drainage power is high-pressure fluid, so if the connection tightness of the jet pipe body and the fluid pipeline is difficult to realize.
In order to rapidly solve the problems of high water content, large porosity and low strength of the soft soil foundation and improve the bearing capacity of the foundation, a construction method capable of rapidly draining water and reinforcing the soft soil foundation is urgently needed.
Disclosure of Invention
Based on the construction method disclosed and practically applied in the present soft soil foundation rapid drainage reinforcement, the invention aims to solve the specific technical problem of how to rapidly reduce the water content in the soft soil body so that the bearing capacity of the soft soil body meets the use requirement of the foundation, and provides a construction method for realizing the rapid drainage of the soft soil body by using the existing materials and equipment.
The invention adopts the following technical scheme:
a construction method for quickly draining and reinforcing soft soil foundation includes the following steps:
firstly, excavating drainage ditches at two sides of a soft soil foundation to be drained, wherein the depth of each drainage ditch exceeds the drainage reinforcement depth of the soft soil foundation by 0.2m so as to ensure the drainage effect of the soft soil foundation;
secondly, drilling a row of circular drill holes in the center of the soft soil foundation by using a drilling machine, wherein the depth of the circular drill holes is the same as the drainage reinforcement depth of the soft soil foundation;
thirdly, pouring a cement slurry layer on the hole wall inside the circular drill hole for wall protection, wherein the thickness of the cement slurry layer is 5mm, and the cement slurry layer mainly serves to provide a closed space for the expanding agent slurry and prevent the expanding agent slurry from seeping into the surrounding soil;
fourthly, preparing an expanding agent slurry after the cement slurry layer is used for protecting the wall for 3 hours, pouring the prepared expanding agent slurry into the circulating drill hole, covering a square steel plate with the thickness of 25mm on the top of the circulating drill hole to prevent the phenomenon of spraying holes in the reaction process of the expanding agent, wherein the expanding agent slurry can be gradually solidified and expanded along with the hydration reaction of the expanding agent slurry and is condensed in the circulating drill hole to form an expansion cylinder, the expansion pressure formed by the expansion cylinder after the hydration reaction can act on the surrounding soft soil body, the pores in the soft soil body around the circulating drill hole can be gradually compacted under the action of the expansion pressure, and the water in the soft soil body can be gradually transferred to the two sides of the foundation under the action of the expansion pressure;
fifthly, after the swelling agent slurry in the circulating drilling holes reacts for 12 hours, respectively drilling a second row of circulating drilling holes towards two sides by taking the circulating drilling hole in the first row as the center according to the row spacing until the distance between the last circulating drilling hole and the edge of the drainage ditch is less than 2 times of the row spacing of the adjacent circulating drilling holes, and stopping drilling the circulating drilling holes;
sixthly, after the swelling agent slurry in the last circular drilling hole reacts for 12 hours, a crushed stone layer with the thickness of 200mm is paved on the surface of the soft soil foundation, rolling operation is carried out, the swelling agent after reaction is in loose granular shape, the swelling agent drilling hole after the reaction is finished can be used as a vertical drainage body, pore water in the soft soil around the drainage body can further flow into the swelling drilling hole under the action of pore water pressure, and then the pore water is drained into drainage ditches at two sides of the foundation through the crushed stone drainage layer, so that consolidation drainage of the soft soil body is further realized.
The distance between the circular drill holes and the row distance between the adjacent circular drill holes are calculated according to the following formula:
wherein L is the interval or row spacing of the circulating drilling holes, d is the diameter of the circulating drilling holes, b is the thickness of the cement slurry layer, and e is the porosity of the soft soil foundation.
The diameter of the circulation drilling hole is 100-300 mm.
The expanding agent slurry is formed by stirring water and a static crushing agent according to the mass ratio of 3: 7.
The invention has the following beneficial effects:
the invention can realize the rapid drainage of the soft soil body by utilizing the existing materials and equipment, extrude water into the drainage ditch one step by one step, use the static breaker, the expansive force is large, the construction process is simple and economic, and the calculation formula of the row spacing among the expanded drill holes is given, the expanded pile can also be used as a vertical drainage body after the use is finished, the water absorption of the expanded pile is discharged to the drainage ditch at both sides through the gravel cushion layer, and the invention can drain water for a long time.
Drawings
FIG. 1 is a front cross-sectional view of a cyclical drilling arrangement of the present invention;
FIG. 2 is a top plan view of the cyclical drilling arrangement of the present invention;
FIG. 3 is an enlarged view of a portion of the cyclical borehole of the present invention;
FIG. 4 is a schematic view of the drainage consolidation mode of the circulation drilling according to the present invention;
wherein: 1-soft soil body to be drained; 2-a drainage ditch; 3-drilling circularly; 4-drilling in a second circulation mode; 5-a gravel cushion layer; 6-a swelling agent slurry; 7-a cement paste layer; 8-square steel plate; 9-a circulation drilling extrusion drainage area; the 10-two cycle drilling squeezes the drainage area.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the following further describes an embodiment of the present invention based on an embodiment example with reference to the accompanying drawings.
The implementation of the construction method for the rapid drainage and reinforcement of the soft soil foundation provided by the invention is as shown in the attached drawings, and the specific method is carried out according to the following steps:
step 1: and (3) excavating drainage ditches 2 at two sides of the soft soil body 1 to be drained, wherein the excavation depth of the drainage ditches 2 needs to exceed the soft soil treatment height by 0.2m so as to ensure the drainage effect of the soft soil body 1 to be drained.
And 3, pouring a cement slurry layer 7 in the circular drill hole 3 for wall protection, wherein the thickness of the cement slurry layer 7 on the wall surface of the drill hole is 5mm, and the cement slurry layer 7 mainly serves to provide a closed space for the expanding agent slurry 6 and prevent the expanding agent slurry 6 from seeping into the surrounding soft soil body 1 to be drained.
And 4, after the cement slurry layer 7 is poured for 3 hours, preparing an expanding agent slurry 6, mixing the expanding agent slurry 6 with water and a static crushing agent, wherein the mass ratio of the expanding agent slurry to the static crushing agent is 3:7, pouring the prepared expanding agent slurry 6 into a circulating drill hole 3, and covering a square steel plate 8 with the thickness of 25mm on the top of the drill hole to prevent the phenomenon of spraying holes in the reaction process of the expanding agent.
And 5, along with the hydration reaction of the swelling agent slurry 6, the swelling agent slurry 6 can be gradually solidified and expanded, a swelling agent column is formed in the drilled hole in a condensation mode, the swelling pressure formed by the swelling agent after the hydration reaction can act on the surrounding soft soil body 1 to be drained, the pores in the surrounding soft soil body 1 to be drained in the drilled hole can be gradually compacted under the action of the swelling pressure, and the water in the soft soil body 1 to be drained can be gradually transferred to the two sides of the foundation under the action of the water swelling pressure.
And 6, after the slurry 6 of the expanding agent in the first circulating drill hole 3 reacts for 12 hours, drilling the second circulating drill holes 4 according to the designed drill hole array pitch, and pouring a cement slurry layer 7 with the thickness of 5mm on the hole wall to protect the wall after drilling the holes. The calculation formula of the drilling row spacing setting is as follows:
wherein L is the distance between the drill holes,d is the diameter of the drilled hole, b is the thickness of the cement slurry retaining wall, and e is the porosity of the soft soil body.
And 7, after the cement slurry layer 7 is poured for 3 hours, preparing an expanding agent slurry 6, wherein the expanding agent slurry 6 is formed by mixing water and a static crushing agent, the mass ratio of the expanding agent slurry to the static crushing agent is 3:7, the prepared expanding agent slurry is poured into the two-cycle drill 4, and a 25 mm-thick square steel plate 8 is covered on the top of the drill, so that the phenomenon of spraying holes in the reaction process of the expanding agent is prevented.
And 7, if the distance between the two-cycle drill hole 4 and the drainage ditch 2 at the two sides of the foundation is more than 2 times of the drill hole distance, then the three-cycle and four-cycle expanding agent drill holes can be continuously constructed until the distance between the expanding agent drill holes and the edge of the drainage ditch 2 is less than 2 times of the drill hole distance.
8, after the last cycle of expansion drilling reaction is carried out for 12 hours, paving a 200mm gravel cushion layer 5 on the surface of the soft foundation, and then carrying out rolling operation on the soft foundation; because the swelling agent after the reaction is in loose granular shape, the swelling agent drill hole after the reaction can be used as a vertical drainage body, pore water in soft soil around the drainage body can further flow into the swelling drill hole under the action of pore water pressure, and then is discharged into drainage ditches at two sides of the foundation through the broken stone drainage layer, so that consolidation drainage of soft soil is further realized.
The following examples further illustrate specific modes of use of the device of the present invention.
The type of the static crushing agent used in the invention is SCA-II type static crushing agent.
Example 1
A roadbed of a certain highway engineering project is a soft soil roadbed with high water content, the water content of the roadbed is 24%, the porosity of a soft soil body is 0.3, the width of the roadbed is 5m, water drainage and consolidation of the soft soil foundation are carried out by adopting expanding agent drilling, the volume expansion rate of the expanding agent is basically 300% when the water-cement ratio of the expanding agent is 3:7, the diameter of the roadbed expanding agent drilling is set to be 300mm, the thickness of a cement mortar protective wall is 5mm, and a calculation formula is set based on the row spacing between the expanding agent drilling:
the row spacing of the expanding agent drill holes can be calculated to be 0.82m, based on the calculation, in the roadbed range, a row of first circulation expansion drill holes are firstly arranged in the center of the roadbed, then after the first circulation expansion drill holes react for 12h, construction of second circulation expansion drill holes is carried out at the position 0.82m away from the first circulation expansion drill holes, similarly, after the second circulation expansion drill holes react for 12h, construction of third circulation expansion drill holes is carried out, circulation is carried out until the sixth circulation expansion drill holes are constructed, at the moment, the distance between the sixth expansion drill holes and drainage ditches on two sides of the roadbed is smaller than the row spacing L between the drill holes, water in soft soil in the roadbed range can be gradually squeezed into the drainage ditches on two sides under the action of expansion pressure through reciprocating circulation, then after the sixth circulation expansion drill holes react for 12h, a crushed stone cushion layer with the thickness of 200mm is paved on the top surface of the roadbed, because the swelling agent after the reaction is in loose granular shape, the swelling agent drill hole after the reaction is finished can be used as a vertical drainage body, pore water in soft soil around the drainage body can further flow into the swelling drill hole under the action of pore water pressure, and then is discharged into drainage ditches at two sides of the foundation through a broken stone drainage layer, so that consolidation drainage of a soft soil body is further realized, the construction of fast drainage and reinforcement of the soft soil foundation is realized, and the bearing capacity of the soft soil foundation meets the use requirement.
Claims (4)
1. A construction method for quickly draining and reinforcing soft soil foundation is characterized in that: the method comprises the following steps:
firstly, excavating drainage ditches at two sides of a soft soil foundation to be drained, wherein the depth of each drainage ditch exceeds the drainage reinforcement depth of the soft soil foundation by 0.2 m;
secondly, drilling a first row of circulating drill holes in the center of the soft soil foundation by using a drilling machine, wherein the depth of the circulating drill holes is the same as the drainage reinforcement depth of the soft soil foundation;
thirdly, pouring a cement slurry layer on the hole wall inside the circular drilled hole for wall protection, wherein the thickness of the cement slurry layer is 5 mm;
fourthly, preparing expanding agent slurry after the cement slurry layer is used for wall protection for 3 hours, pouring the prepared expanding agent slurry into the circulating drill hole, and covering a square steel plate with the thickness of 25mm on the top of the circulating drill hole;
fifthly, after the swelling agent slurry in the circulating drilling holes reacts for 12 hours, respectively drilling a second row of circulating drilling holes towards two sides by taking the circulating drilling holes in the first row as the center according to the row spacing, repeating the steps to continue the construction until the distance between the last circulating drilling hole and the edge of the drainage ditch is less than 2 times of the row spacing of the adjacent circulating drilling holes, and stopping drilling the circulating drilling holes;
and sixthly, after the swelling agent slurry in the last circular drilling hole reacts for 12 hours, paving a gravel layer with the thickness of 200mm on the surface of the soft soil foundation, and performing rolling operation to realize consolidation drainage of the soft soil body.
2. The construction method for quickly draining and reinforcing the soft soil foundation according to claim 1, characterized in that: the distance between the circular drill holes and the row distance between the adjacent circular drill holes are calculated according to the following formula:
wherein L is the interval or row spacing of the circulating drilling holes, d is the diameter of the circulating drilling holes, b is the thickness of the cement slurry layer, and e is the porosity of the soft soil foundation.
3. The construction method for quickly draining and reinforcing the soft soil foundation according to claim 1, characterized in that: the diameter of the circulation drilling hole is 100-300 mm.
4. The construction method for quickly draining and reinforcing the soft soil foundation according to claim 1, characterized in that: the expanding agent slurry is formed by stirring water and a static crushing agent according to the mass ratio of 3: 7.
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| CN202010961302.0A CN112049103B (en) | 2020-09-14 | 2020-09-14 | Construction method for rapid drainage and reinforcement of soft soil foundation |
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| CN202010961302.0A CN112049103B (en) | 2020-09-14 | 2020-09-14 | Construction method for rapid drainage and reinforcement of soft soil foundation |
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| CN112049103A true CN112049103A (en) | 2020-12-08 |
| CN112049103B CN112049103B (en) | 2022-02-18 |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112575638A (en) * | 2020-12-11 | 2021-03-30 | 宁波华康陆鼎建设有限公司 | Roadbed reinforcing structure adopting steel reinforcement cage bamboo shoot piles and construction process of roadbed reinforcing structure |
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| BR9905711A (en) * | 1999-12-08 | 2001-07-24 | Joao Duarte Filho Guimaraes | Soil consolidation process by physicochemical expansion with simultaneous drainage |
| CN102817353A (en) * | 2012-08-03 | 2012-12-12 | 华侨大学 | Composite soft clay foundation |
| CN204059124U (en) * | 2014-08-06 | 2014-12-31 | 冠鲁建设股份有限公司 | A kind of sand drain strong rammer grouting behind shaft or drift lining foundation reinforcing structure |
| CN206859199U (en) * | 2017-05-02 | 2018-01-09 | 华侨大学 | A kind of composite foundation |
| CN108867619A (en) * | 2018-06-14 | 2018-11-23 | 浙江大学 | Drainage plate and method with water uptake expansion material under piling prepressing |
| CN111379253A (en) * | 2019-10-25 | 2020-07-07 | 重庆大学 | Construction method for high-speed railway expanded cement slurry post-grouting discrete material pile composite foundation |
-
2020
- 2020-09-14 CN CN202010961302.0A patent/CN112049103B/en active Active
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| BR9905711A (en) * | 1999-12-08 | 2001-07-24 | Joao Duarte Filho Guimaraes | Soil consolidation process by physicochemical expansion with simultaneous drainage |
| CN102817353A (en) * | 2012-08-03 | 2012-12-12 | 华侨大学 | Composite soft clay foundation |
| CN204059124U (en) * | 2014-08-06 | 2014-12-31 | 冠鲁建设股份有限公司 | A kind of sand drain strong rammer grouting behind shaft or drift lining foundation reinforcing structure |
| CN206859199U (en) * | 2017-05-02 | 2018-01-09 | 华侨大学 | A kind of composite foundation |
| CN108867619A (en) * | 2018-06-14 | 2018-11-23 | 浙江大学 | Drainage plate and method with water uptake expansion material under piling prepressing |
| CN111379253A (en) * | 2019-10-25 | 2020-07-07 | 重庆大学 | Construction method for high-speed railway expanded cement slurry post-grouting discrete material pile composite foundation |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN112575638A (en) * | 2020-12-11 | 2021-03-30 | 宁波华康陆鼎建设有限公司 | Roadbed reinforcing structure adopting steel reinforcement cage bamboo shoot piles and construction process of roadbed reinforcing structure |
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| CN112049103B (en) | 2022-02-18 |
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