CN113309070A - Drainage moso bamboo for soft soil foundation treatment and construction method thereof - Google Patents
Drainage moso bamboo for soft soil foundation treatment and construction method thereof Download PDFInfo
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- CN113309070A CN113309070A CN202110608816.2A CN202110608816A CN113309070A CN 113309070 A CN113309070 A CN 113309070A CN 202110608816 A CN202110608816 A CN 202110608816A CN 113309070 A CN113309070 A CN 113309070A
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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 discloses drainage moso bamboo for soft soil foundation treatment and a construction method thereof. The outer circumference of each internode in the direction from the top of the bamboo pole to the bottom of the bamboo pole is provided with a drain hole, and the outer circumference of the internode provided with the drain hole is sleeved with geotextile; except that one to two bamboo joints close to the bottom of the bamboo pole are not provided with round holes in the direction from the top of the bamboo pole to the bottom of the bamboo pole, all the other bamboo joints are provided with a round hole, and a vertical drainage channel is formed by penetrating the round holes from the top of the bamboo pole to the internodes in the direction from the bottom of the bamboo pole along the axial direction. The invention has the advantages of good foundation treatment effect, high-efficiency and stable drainage, simple and convenient operation, low carbon, environmental protection and wide application range.
Description
Technical Field
The invention belongs to drainage moso bamboos in the field of foundation treatment in geotechnical engineering, and particularly relates to drainage moso bamboos for soft soil foundation treatment and a construction method thereof.
Background
In order to ensure the stability of the supply chain, the industry chain is reconstructed towards globalization, diversification and localization, and the coastal areas at shipping nodes are developed again. Increasingly, large logistics centers, bonded warehouses, industrial plants and the like in units of square kilometers are being built in such coastal soft clay areas. Soft soil, as a typical poor engineering soil body, has the problems of poor permeability, low shear strength, high compressibility and the like. At present, the most common treatment method of the soft soil foundation is drainage consolidation, a plastic drainage plate is mostly adopted, and drainage of the soil body is accelerated by preloading or vacuum preloading. However, this method has some drawbacks: 1. the plastic drainage plate is low in rigidity, so that bending is easy to occur in the process of driving or draining, and the vacuum degree cannot be maintained after bending, so that the drainage effect is reduced sharply. 2. The main body of the plastic drainage plate is formed by polymerizing polypropylene and polyethylene, is a non-degradable high polymer material specified by the national development and modification Commission, continuously discharges carbon in the production and use process, has obvious influence on the environment, and is not in accordance with the target of carbon neutralization in 2030 and 2060, which is clearly established by fourteen-five plans in China. 3. The plastic drainage plate and the soft soil can not form a composite foundation.
The moso bamboo is widely applied to structural engineering as a green low-carbon material with certain toughness, but is less applied to the treatment of soft soil foundations, and mostly only plays the roles of reinforcement and support, or is matched with pile foundations to reduce the soil squeezing effect. The drainage channel has almost no drainage function, only depends on a gap between the moso bamboos or is additionally provided with a geotextile bag and the like to form a drainage channel, and the drainage channel has poor stability and weak drainage effect after being used for a long time. Therefore, the development of a soft soil foundation treatment method which is low in carbon and can effectively drain and consolidate water is of great significance.
Disclosure of Invention
In order to solve the problems in the background art, the invention provides a drainage moso bamboo for treating a soft soil foundation and a construction method thereof. The degradable mao bamboo with negative carbon emission is applied to the soft soil foundation treatment, the yield of the mao bamboo in China is huge, the growth speed of the mao bamboo is high, and the mao bamboo absorbs carbon in the growth process. The moso bamboo with a certain size is selected to ensure rigidity and toughness, is not easy to bend in the processes of beating and vacuum setting, and can better keep the vacuum degree. Vertical and radial drainage channels are formed by the vertical and lateral holes of the moso bamboo, the degradable geotextile is wrapped to better filter reversely, small holes are prevented from being blocked, and the long-term stable work of the drainage channels is ensured. The vacuum device has a water-vapor separation effect, so that drainage and vacuum can be performed alternately without manual switching. After the drainage consolidation is finished, the moso bamboo and the soil body form a composite foundation, and the composite foundation has certain bearing capacity. With the lapse of time, the foundation settlement is gradually stabilized, and the moso bamboo and the geotextile are degraded in the soil body, so that the low-carbon soft soil foundation treatment is realized.
The technical scheme of the invention is as follows:
a drainage mao bamboo for soft soil foundation handles
Pretreating the bamboo rod, and then uniformly forming drain holes at intervals along the circumferential direction on the outer circumference of each internode from the top of the bamboo rod to the bottom of the bamboo rod, wherein the internodes are parts between two bamboo joints, and the outer circumference of the internode provided with the drain holes is externally sleeved with geotextile for preventing clogging; one or two bamboo joints near the bottom of the bamboo pole are not provided with round holes from the top of the bamboo pole to the bottom of the bamboo pole, and each of the other bamboo joints is provided with a bamboo joint with an outer diameter of
The round hole is communicated with the round hole from the top of the bamboo rod along the axial direction to the internode on the bottom of the bamboo rod to form a vertical drainage channel with the length of l.
The bamboo pole is made of moso bamboo, leaves of the moso bamboo are removed, the outer diameter D of the bamboo pole is 5-20cm, and the pretreatment is to cut the bamboo pole to enable the length L of the bamboo pole to be 5-10 m.
The diameter d of each drain hole is less than or equal to 2cm, the distance a between every two adjacent drain holes along the axial direction of the bamboo rod meets the condition that a is less than or equal to 3d and less than or equal to h, wherein h represents the length between every two adjacent bamboo joints; the number n of the drain holes on the outer circumference between two adjacent bamboo joints of the bamboo pole is less than or equal to 4.
The length L of the vertical drainage channel is smaller than the length L of the bamboo rod, and the outer diameter of the vertical drainage channel is equal to the outer diameter of the round hole and smaller than the inner diameter of the bamboo rod.
The geotextile for preventing clogging is made of degradable non-woven fabric.
Second, construction method of drainage moso bamboo for soft soil foundation treatment
The method comprises the following specific steps:
step S1: the bottom of each bamboo pole is respectively connected with the pile head of each bamboo pole, then each bamboo pole is sleeved with a sleeve, static pressure is carried out through a small-sized loading type pile driver to form a plurality of bamboo poles with the sleeves in a conformal mode, then static pressure is carried out through the small-sized loading type pile driver, and the bamboo poles with the sleeves are respectively implanted into soft soil;
step S2: pulling out the sleeve by a small loading type pile driver to enable the bamboo rod and the pile head to be left in the soft soil;
step S3: connecting the upper end of a bamboo rod to vacuum equipment, then starting a vacuum pump in the vacuum equipment to ensure that the interior of the bamboo rod is vacuumized, wherein water in soft soil in the circumferential direction of the bamboo rod gradually permeates into a vertical drainage channel after passing through a drainage hole and anti-clogging geotextile, when the water level exceeds the bottom of a branch conduit, the water permeated into the vertical drainage channel is sequentially pumped into a water-vapor separation barrel of the vacuum equipment along the branch conduit and a main conduit under the action of negative pressure, then the water level in the vertical drainage channel is reduced, a vacuum environment is formed in the bamboo rod again, and the water is circulated repeatedly until the water in the water-vapor separation barrel of the vacuum equipment is not increased or the consolidation degree of the soft soil reaches a design value;
step S4: and removing the vacuum equipment, and backfilling the gravel cushion layer and the grid on the ground to reach the designed elevation.
The sleeve, the pile head and the water-vapor separation barrel are all made of steel, and the pile head is provided with the expansion head, so that the bamboo pole can be driven into a soil body.
In the step S3, the step of connecting the bamboo poles to the vacuum equipment specifically includes: the vacuum equipment comprises a vacuum pump, a main conduit, branch conduits, a water-vapor separation barrel and a rubber seal ring, wherein one end of each branch conduit is vertically inserted into a position 5-10cm above the bottom surface of a drainage channel of each bamboo pole, the other end of each branch conduit extends out of the top of each bamboo pole, the extending heights of the branch conduits are the same, the outer wall of each branch conduit and the top of each bamboo pole are sealed by the rubber seal ring, then each branch conduit is connected onto the main conduit, two openings are arranged at the top of the water-vapor separation barrel, namely a water-vapor separation barrel A opening and a water-vapor separation barrel C opening, a water-vapor separation barrel B opening with a valve is arranged on the circumferential side surface close to the bottom of the water-vapor separation barrel, one end of the main conduit connected with the branch conduits is inserted into the water-vapor separation barrel A opening, water in the drainage channel in the bamboo poles is pumped into the water-vapor separation barrel A opening along the branch conduits and the main conduit, one end of the other main guide pipe is inserted into the port C of the water-vapor separation barrel, the other end of the other main guide pipe is connected with a vacuum pump, a rubber sealing ring is used between the main guide pipe connected with the branch guide pipe and the top of the port A of the water-vapor separation barrel for sealing treatment, and a rubber sealing ring is used between the other main guide pipe and the top of the port C of the water-vapor separation barrel for sealing treatment; and in the vacuum process, intermittently opening a valve of a port B of the water-vapor separation barrel to discharge liquid in the water-vapor separation barrel. When the vacuum pumping is carried out, water in the drainage channels in the bamboo poles is pumped into the water-vapor separation barrel along the branch pipes and the main pipe which is jointly connected with the branch pipes, and the water is not pumped into the water-vapor separation barrel one by one. The main conduit connected with the branch conduit can be inserted into the bottom of the water-vapor separation barrel, the other main conduit can not be inserted into the bottom of the water-vapor separation barrel, and enough space is reserved between the other main conduit and the bottom of the water-vapor separation barrel, so that liquid in the water-vapor separation barrel is prevented from being directly sucked into the vacuum pump.
In the step S1, the distance between two adjacent bamboo poles implanted in the soft soil is 3D-8D, where D is the outer diameter of the bamboo pole.
Calibrating 5cm-7.5cm as class I rod, 7.5cm-10.5cm as class II rod, 10.5cm-13.5cm as class III rod, and 13.5cm-16cm as class IV rod. The sleeve is made of steel, the diameter of the sleeve is slightly larger than the diameter of each type of bamboo pole, the length of the sleeve exceeds one third of the total length of the bamboo poles, and the sleeve has the functions of ensuring the perpendicularity of the bamboo poles and avoiding bending of the bamboo poles when the bamboo poles are driven into a soil body.
The main conduit and the branch conduit are PU air pipes, the diameter of the branch conduit is smaller than that of the bamboo pole, and the diameter of the main conduit is equal to that of the port C of the water-vapor separation barrel and the port A of the water-vapor separation barrel.
The common soft soil foundation treatment method in the engineering at present is a consolidation drainage method, and a plastic drainage plate is often used as a drainage body in the method, so that the following defects exist: 1. the plastic drainage plate has low rigidity, and is easy to bend, so that the vacuum degree cannot be maintained, and the drainage effect is rapidly reduced. 2. The main body of the plastic drainage plate is formed by polymerizing polypropylene and polyethylene, and carbon emission is continuously carried out in the production and use processes, so that the soil body and the atmospheric environment are damaged. 3. The plastic drainage plate and the soft soil can not form a composite foundation. Therefore, on the basis of ensuring the soft foundation treatment effect, the method of degradable low carbon emission is adopted as much as possible to carry out drainage consolidation treatment on the soft foundation.
The drainage moso bamboo disclosed by the invention absorbs carbon dioxide in the growth process, does not additionally discharge carbon in the use process, and is a green, environment-friendly, low-carbon and degradable material. The bamboo rod has certain rigidity and toughness, is not easy to bend in the construction and use processes, can keep better vacuum degree and a complete drainage channel, is matched with degradable geotextile, prevents the drainage hole from being silted up, and ensures that the drainage channel can effectively work for a long time. After the drainage consolidation is finished, the drainage moso bamboo and the soil body form a composite foundation, and the composite foundation has certain bearing capacity. With the lapse of time, the foundation settlement is gradually stabilized, and the moso bamboo and the geotextile are degraded in the soil body, so that the low-carbon soft soil foundation treatment is realized.
The water content of the soft clay in coastal areas is generally 60-120%, and I-IV poles can be selected according to the water content and the soil property. The higher region of water content, the soil body is softer, can squeeze into the bamboo pole of great diameter, and drainage channel area is bigger, and drainage speed is faster, and thicker bamboo pole can provide stronger vertical braces. The lower region of water content, the soil body is harder, adopts the bamboo pole of less diameter to change into the soil body, and crowded soil effect is littleer, and the control post-construction that can be better subsides after the fine setting. Tests prove that the soil with the water content of 60-75% adopts I-type rods, the soil with the water content of 75-90% adopts II-type rods, the soil with the water content of 90-105% adopts III-type rods, and the soil with the water content of 105-120% adopts IV-type rods, so that the effect is better.
The invention utilizes the toughness of the moso bamboo and is matched with the silt-proof geotextile to ensure that the drainage channel can work stably and efficiently for a long time; the vacuum device has a water-vapor separation effect, and drainage and vacuum are automatically alternated; as time goes on, the moso bamboo and the geotextile are degraded in the soil body; the construction method has strong applicability, and the I-type rods to the IV-type rods can be selected according to the water content and the soil property. The invention has the advantages of good foundation treatment effect, high-efficiency and stable drainage, simple and convenient operation, low carbon, environmental protection and wide application range.
The invention has the beneficial effects that:
(1) the carbon emission is low, and the national carbon neutralization target is met. The drainage moso bamboo disclosed by the invention absorbs carbon dioxide in the growth process, does not additionally discharge carbon in the use process, and is a green environment-friendly low-carbon material.
(2) The soft foundation treatment effect is good. The drainage channel of the drainage moso bamboo works stably for a long time and can accelerate the drainage consolidation of soft soil. After the consolidation is finished, a composite foundation is formed with the soft soil, and the bearing capacity of the soft soil foundation is improved.
(3) Simple manufacture and convenient construction. The mao bamboo can be made into drainage mao bamboo available for engineering only by three steps of leaf removal, hole punching and film covering. When the pile is driven, the steel sleeve and the pile head are used for assisting, so that the pile can be driven into soft soil quickly without soil squeezing effect.
(4) The construction method is easy to popularize and has universal applicability in coastal areas. Most of coastal areas are soft clay, the water content is generally 60-120%, and I-IV poles can be selected according to the water content and the soil property.
Drawings
FIG. 1 is a schematic view of the structure of a water-draining moso bamboo of the present invention;
FIG. 2 is a schematic view of a vacuum apparatus and its connection;
FIG. 3(1) is a schematic diagram of the evacuation process during the evacuation process;
FIG. 3(2) is a schematic diagram of a water pumping process during the vacuum process;
FIG. 4(1) is a schematic view of a step of the construction method of the present invention;
FIG. 4(2) is a schematic view of the second step of the construction method of the present invention;
FIG. 4(3) is a schematic view of the third step of the construction method of the present invention;
FIG. 4(4) is a diagram schematically illustrating a fourth step of the construction method of the present invention;
FIG. 5(1) is a graph showing the results of vacuum degree tests of different depths in a plastic drainage board treatment method;
FIG. 5(2) is a graph showing the results of vacuum degree tests at different depths in a drainage phyllostachys pubescens treatment process;
FIG. 6 is a graph showing the results of a comparison test between the water pumping amount of the plastic drainage plate treatment method and the drainage moso bamboo treatment method;
FIG. 7 is a graph showing the results of a comparative test of the amount of surface subsidence between the plastic drainage board treatment method and the drainage moso bamboo treatment method;
FIG. 8(1) is a graph showing the shear strength test results of the cross plate in the plastic drainage plate treatment method;
FIG. 8(2) is a graph showing the results of shear strength tests of the drainage bamboo treatment method.
In the figure, 1-bamboo pole; 2-a drain hole; 3-bamboo joint; 4-anti-clogging geotextile; 5-vertical drainage channels; 6-a sleeve; 7-pile head; 8-vacuum equipment; 9-a vacuum pump; 10-a main conduit; 11-branch catheter; 12-a water-vapor separation barrel; 13-rubber sealing ring; 14-a port A of a water-vapor separation barrel; 15-water-vapor separation barrel port B; 16-a water-vapor separation barrel opening C; 17-small loader pile driver; 18-gravel cushion and grid.
Detailed Description
The technical means adopted by the invention to achieve the predetermined purpose are further described below by matching with the preferred embodiments of the invention.
As shown in fig. 1, a bamboo pole 1 is pretreated, and then drain holes 2 are uniformly arranged on the outer circumference of each internode along the direction from the top of the bamboo pole 1 to the bottom of the bamboo pole 1 at intervals along the circumferential direction, wherein the internode is the part between two bamboo joints, and the outer circumference of the internode at the position where the drain holes 2 are arranged is sleeved with a geotextile 4 for preventing clogging; except that the round holes are not formed in one to two bamboo joints 3 close to the bottom of the bamboo rod 1 from the top of the bamboo rod 1 to the bottom of the bamboo rod 1, each of the rest bamboo joints 3 is provided with a bamboo joint 3 with an outer diameter of
The round hole is communicated with the internode in the direction from the top of the bamboo pole 1 to the bottom of the bamboo pole 1 along the axial direction to form a vertical drainage channel 5 with the length of l.
In specific implementation, the length L of the vertical drainage channel 5 is less than the length L of the bamboo rod 1, and the outer diameter of the vertical drainage channel 5 is equal to the outer diameter of the round hole and less than the inner diameter of the bamboo rod 1. The diameter d of each drain hole 2 is less than or equal to 2cm, the distance a between every two adjacent drain holes 2 along the axial direction of the bamboo rod 1 satisfies the condition that a is less than or equal to 3d and less than or equal to h, wherein h represents the length between every two adjacent bamboo joints; the number n of the water discharge holes 2 on the outer circumference between two adjacent bamboo joints 3 of the bamboo rod 1 is less than or equal to 4. The geotextile 4 for preventing clogging is made of degradable non-woven fabric.
The specific implementation of the bamboo pole 1 is made of moso bamboo, the outer diameter D of the bamboo pole 1 is 5-20cm, and the pretreatment is to cut the bamboo pole 1 to enable the length L of the bamboo pole 1 to be 5-10 m.
The sleeve is made of steel, the diameter of the sleeve is slightly larger than the diameter of each type of bamboo pole, the length of the sleeve exceeds one third of the total length of the bamboo poles, and the sleeve has the functions of ensuring the perpendicularity of the bamboo poles and avoiding bending of the bamboo poles when the bamboo poles are driven into a soil body.
The main conduit and the branch conduit are PU air pipes, the diameter of the branch conduit is smaller than that of the bamboo pole, and the diameter of the main conduit is equal to that of the port C of the water-vapor separation barrel and the port A of the water-vapor separation barrel.
As shown in fig. 4, the construction method of the drainage moso bamboo for soft soil foundation treatment adopts the following specific steps:
step S1: the bottom of each bamboo pole 1 is respectively connected with the pile head 7, then a sleeve 6 is sleeved on each bamboo pole 1, static pressure is carried out through a small loading type pile driver 17, each bamboo pole 1, the pile head 7 connected with each bamboo pole 1 and the sleeve 6 sleeved on each bamboo pole 1 are respectively implanted into soft soil together, the distance between every two adjacent bamboo poles 1 implanted into the soft soil is 3D-8D, and D is the outer diameter of each bamboo pole 1.
Step S2: the sleeve 6 is pulled out through a small loading type pile driver 17, so that the bamboo pole 1 and the pile head 7 are left in the soft soil;
step S3: connecting the upper end of a bamboo rod 1 to a vacuum device 8, then starting a vacuum pump 9 in the vacuum device 8 to ensure that the interior of the bamboo rod 1 is vacuumized, water in the soft soil in the circumferential direction of the bamboo rod 1 gradually permeates into a vertical drainage channel 5 after passing through a drainage hole 2 and an anti-clogging geotextile 4, when the water level exceeds the bottom of a branch conduit 11, due to the action of negative pressure, the water permeating into the vertical drainage channel 5 is pumped into a water-vapor separation barrel 12 of the vacuum device 8 along the branch conduit 11 and a main conduit 10 in sequence, then the water level in the vertical drainage channel 5 is lowered, a vacuum environment is formed in the bamboo rod 1 again, and the water is circulated repeatedly until the water in the water-vapor separation barrel 11 of the vacuum device 8 is not increased any more or the consolidation degree of the soft soil reaches;
step S4: and removing the vacuum equipment 8, and backfilling a gravel cushion layer and the grating 18 on the ground to reach the designed elevation.
As shown in fig. 2 and 3, in step S3, the step of connecting the bamboo pole 1 to the vacuum device 8 includes: the vacuum equipment 8 comprises a vacuum pump 9, a main conduit 10, branch conduits 11, a water-vapor separation barrel 12 and a rubber sealing ring 13, one end of each branch conduit 11 is vertically inserted into a position 5-10cm above the bottom surface of a drainage channel 5 of each bamboo pole 1, the other end of each branch conduit 11 extends out of the top of each bamboo pole 1, the extending heights of the branch conduits 11 are the same, the outer wall of each branch conduit 11 and the top of each bamboo pole 1 are sealed by the rubber sealing ring 13, then each branch conduit 11 is connected onto the main conduit 10, the top of the water-vapor separation barrel 12 is provided with two openings, namely a water-vapor separation barrel A opening 14 and a water-vapor separation barrel C opening 16, the circumferential side surface close to the bottom of the water-vapor separation barrel 12 is provided with a water-vapor separation barrel B opening 15 with a valve, one end of the main conduit 10 connected with the branch conduits 11 is inserted into the water-vapor separation barrel A opening 14, one end of the other main guide pipe 10 is inserted into a water-vapor separation barrel C port 16, the other end of the other main guide pipe 10 is connected with a vacuum pump 9, a rubber sealing ring 13 is used for sealing between the main guide pipe 10 connected with the branch guide pipe 11 and the top of a water-vapor separation barrel A port 14, and a rubber sealing ring 13 is used for sealing between the other main guide pipe 10 and the top of the water-vapor separation barrel C port 16; and intermittently opening a valve of the port B15 of the water-vapor separation barrel in the vacuum process, and discharging the liquid in the water-vapor separation barrel 12. The main conduit 10 connected with the branch conduit 11 can be inserted into the bottom of the water-vapor separation barrel 12, and the other main conduit 10 can not be inserted into the bottom of the water-vapor separation barrel 12, so that enough space is left between the main conduit and the bottom of the water-vapor separation barrel 12 to prevent the liquid in the water-vapor separation barrel 12 from being directly sucked into the vacuum pump 9.
In the specific implementation, when the vacuum pumping is carried out, water in the drainage channels in the bamboo poles is pumped into the water-vapor separation barrel at the same time along the branch pipes and the main pipe which is jointly connected with the branch pipes, but the water is not pumped into the water-vapor separation barrel one by one. The main conduit connected with the branch conduit can be inserted into the bottom of the water-vapor separation barrel, the other main conduit can not be inserted into the bottom of the water-vapor separation barrel, and enough space is reserved between the other main conduit and the bottom of the water-vapor separation barrel, so that liquid in the water-vapor separation barrel is prevented from being directly sucked into the vacuum pump.
The sleeve 6, the pile head 7 and the water-vapor separation barrel 12 are made of steel.
Example 1: laboratory test
Taking a soft clay soil sample at a construction site, and putting the soft clay soil sample into a model box. The mixture ratio of the clay samples with 4 typical water contents and the basic parameters of the soft clay soil samples are shown in Table 1.
TABLE 1 basic parameters of soft clay soil samples
| Soil sample numbering | Water content/%) | Severe kN m-3 | Specific gravity of | Plastic limit/%) | Liquid limit/%) |
| ① | 67.5 | 15.75 | 2.71 | 25 | 54 |
| ② | 82.5 | 16.12 | 2.69 | 24 | 55 |
| ③ | 97.5 | 18.12 | 2.71 | 25 | 54 |
| ④ | 112.5 | 18.05 | 2.72 | 25 | 54 |
The protocol was as follows: selecting drainage moso bamboos with different diameters to carry out a single bamboo pole test, classifying the bamboo poles with different diameters, wherein 5cm-7.5cm is a class I pole, 7.5cm-10.5cm is a class II pole, 10.5cm-13.5cm is a class III pole, and 13.5cm-16cm is a class IV pole, uniformly cutting the bamboo poles with different classes into 8m in length, and driving the bamboo poles into 4 soil samples. Vacuumizing, draining and solidifying for 350h, measuring the punching power consumption and the shearing strength of the solidified cross plate, and calculating and normalizing to obtain the optimal bamboo rod category of the soft soil with different water contents.
TABLE 2 Power consumption for soft clay soil sample
| ① | ② | ③ | ④ | |
| Class I rod | 235.2J | 211.68J | 190.51J | 152.41J |
| Class II rod | 313.6J | 282.24J | 254.02J | 177.81J |
| Class III rod | 392.1J | 352.89J | 317.60J | 222.32J |
| IV-class rod | 470.4J | 423.09J | 380.78J | 266.54J |
TABLE 3 shear Strength of different types of bars
| ① | ② | ③ | ④ | |
| Class I rod | 9.8kPa | 6.17kPa | 5.56kPa | 4.32kPa |
| Class II rod | 11.76kPa | 11.76kPa | 8.47kPa | 4.07kPa |
| Class III rod | 13.07kPa | 11.03kPa | 13.23kPa | 8.34kPa |
| IV-class rod | 11.76kPa | 14.10kPa | 13.49kPa | 11.11kPa |
TABLE 4 shear strength of different types of rods and normalized ratio of driving power consumption
| ① | ② | ③ | ④ | |
| |
1 | 0.7 | 0.7 | 0.68 |
| Class II rod | 0.9 | 1 | 0.8 | 0.55 |
| Class III rod | 0.8 | 0.75 | 1 | 0.9 |
| IV-class rod | 0.6 | 0.8 | 0.85 | 1 |
The indoor test results show that: the smaller the diameter of the drainage moso bamboo is, the higher the water content of the soft soil is, the lower the driving power consumption is, but the lower the shear strength is increased, and vice versa. Normalized by the ratio of intensity to power consumption, one can derive: the soil body with the water content of 60% -75% adopts I-type rods, the soil body with the water content of 75% -90% adopts II-type rods, the soil body with the water content of 90% -105% adopts III-type rods, and the soil body with the water content of 105% -120% adopts IV-type rods, so that the foundation treatment effect is better, and the cost performance is highest.
Example 2: field test
The upper layer of the engineering field is provided with silt soft soil with the depth of 20m, and a plastic drainage plate and drainage moso bamboo are respectively adopted to treat 100m2And (4) a region. The natural water content of the soil body is 104.8 percent, the shear strength of the cross plate is 2.25kPa, and the gravity is 14.43 kN.m-3The liquid limit is 56 percent and the plastic limit is 27 percent.
The content of the specific test comprises: (1) in the reinforcing test process, under two different treatment methods, the vacuum degree and the real-time water discharge at different depths of the soil body are shown in the figure 5 and the figure 6. (2) After the consolidation test, the shear strength of the cross plate and the soil surface settlement of two different treatment methods after the consolidation are measured, and the test results are shown in fig. 7 and 8.
The field test result shows that along with the increase of the depth, the degree of vacuum attenuation of the drainage moso bamboo is smaller than that of the plastic drainage plate, and the lowest vacuum degree is about 15% higher than that of the plastic drainage plate. The water pumping time can be prolonged by 70 hours, and the total water pumping amount is increased by 55 percent. And because the drainage mao bamboo and the soft foundation form a composite foundation and share settlement together, the settlement of the ground surface after consolidation is 15 percent less than that of the plastic drainage plate. The shear strength of the treated soft soil foundation is improved by 3.5 times at most, and the strength is smaller than that of the plastic drainage plate along with the distance attenuation degree.
As can be seen from examples 1 and 2,
the drainage channel of the drainage moso bamboo can work stably for a long time, has strong capability of maintaining vacuum degree, and can accelerate the drainage consolidation of soft soil. After the consolidation is finished, the composite foundation is formed with the soft soil, the surface settlement is small, and the bearing capacity of the soft soil foundation is obviously improved.
Drainage mao bamboo application scope is wide, and to the higher region of water content, the soil body is softer, squeezes into the bamboo pole of great diameter, and drainage channel area is bigger, and drainage speed is faster, and thicker bamboo pole can provide stronger vertical braces. The lower region of water content, the soil body is harder, adopts the bamboo pole of less diameter to change into the soil body, and crowded soil effect is littleer, and the control post-construction that can be better subsides after the fine setting.
Although the present invention has been described with reference to the preferred embodiments, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the invention as defined by the appended claims.
Claims (9)
1. The utility model provides a drainage mao bamboo for soft soil foundation handles which characterized in that: pretreating the bamboo rod (1), then uniformly opening drain holes (2) at intervals along the circumferential direction from the top of the bamboo rod (1) to the outer circumference of each internode in the direction of the bottom of the bamboo rod (1), and sleeving a geotextile (4) outside the outer circumference of the internode with the drain holes (2);
except that round holes are not formed in one to two bamboo joints (3) close to the bottom of the bamboo rod (1) from the top of the bamboo rod (1) to the bottom of the bamboo rod (1), each of the rest bamboo joints (3) is provided with a bamboo joint (3) with an outer diameter of one
The round hole enables an inner cavity between the joints from the top of the bamboo rod (1) to the bottom of the bamboo rod (1) along the axial direction to be communicated with the round hole to form a vertical drainage channel (5).
2. A drainage mao bamboo for soft soil foundation treatment according to claim 1, wherein: the bamboo pole (1) is made of moso bamboo, the outer diameter D of the bamboo pole (1) is 5-20cm, and the pretreatment is to cut the bamboo pole (1) to enable the length L of the bamboo pole (1) to be 5-10 m.
3. A drainage mao bamboo for soft soil foundation treatment according to claim 1, wherein: the diameter d of each drain hole (2) is less than or equal to 2cm, the distance a between every two adjacent drain holes (2) along the axial direction of the bamboo rod (1) meets the condition that a is less than or equal to 3d and less than or equal to h, wherein h represents the length between every two adjacent bamboo joints; the number n of the drain holes (2) on the outer circumference between two adjacent bamboo joints (3) of the bamboo rod (1) is less than or equal to 4.
4. A drainage mao bamboo for soft soil foundation treatment according to claim 1, wherein: the length L of the vertical drainage channel (5) is less than the length L of the bamboo rod (1), and the outer diameter of the vertical drainage channel (5) is equal to the outer diameter of the round hole and is less than the inner diameter of the bamboo rod (1).
5. A drainage mao bamboo for soft soil foundation treatment according to claim 1, wherein: the geotextile (4) is made of degradable non-woven fabric.
6. The construction method of the drainage phyllostachys pubescens for soft soil foundation treatment as claimed in any one of claims 1 to 5, characterized in that: the method comprises the following specific steps:
step S1: the bottom of each bamboo pole (1) is respectively connected with the pile head (7), then a sleeve (6) is sleeved on each bamboo pole (1) to form a plurality of bamboo poles (1) with the sleeves (6), then static pressure is carried out through a small loading type pile driver (17), and the bamboo poles (1) with the sleeves (6) are respectively implanted into soft soil;
step S2: the sleeve (6) is pulled out through a small loading type pile driver (17), so that the bamboo rod (1) and the pile head (7) are left in the soft soil;
step S3: the bamboo pole (1) is connected to a vacuum device (8), then a vacuum pump (9) in the vacuum device (8) is started to enable the interior of the bamboo pole (1) to be vacuumized, water in the soft soil in the circumferential direction of the bamboo pole (1) penetrates into the vertical drainage channel (5) after passing through the drainage hole (2) and the geotextile (4), the water penetrating into the vertical drainage channel (5) is pumped into the vacuum device (8), then the water level in the vertical drainage channel (5) is reduced, a vacuum environment is formed in the bamboo pole (1) again, and the bamboo pole is circulated repeatedly until the water in the vacuum device (8) is not increased any more or the consolidation degree of the soft soil reaches a design value;
step S4: and removing the vacuum equipment (8), and backfilling the gravel cushion layer and the grating (18) to reach the designed elevation.
7. The method of claim 6, wherein the method comprises the steps of: the sleeve (6), the pile head (7) and the water-vapor separation barrel (12) are all made of steel.
8. The method of claim 6, wherein the method comprises the steps of: in the step S3, the step of connecting the bamboo pole (1) to the vacuum device (8) specifically includes: the vacuum equipment (8) comprises a vacuum pump (9), a main conduit (10), branch conduits (11), a water-vapor separation barrel (12) and rubber sealing rings (13), one ends of a plurality of branch conduits (11) are respectively vertically inserted into positions 5-10cm above the bottom surface of a drainage channel (5) of each bamboo rod (1), the other ends of the branch conduits (11) respectively extend out of the top of each bamboo rod (1), the extending heights of the branch conduits (11) are the same, a rubber sealing ring (13) is adopted to seal the space between the outer wall of each branch conduit (11) and the top of each bamboo rod (1), then each branch conduit (11) is connected onto the main conduit (10), the top of the water-vapor separation barrel (12) is provided with two ports, namely a port (14) of the water-vapor separation barrel and a port (16), a port (15) of the water-vapor separation barrel with a valve is arranged on the side surface close to the bottom of the water-vapor separation barrel (12), one end of a main guide pipe (10) connected with a branch guide pipe (11) is inserted into a port A (14) of a water-vapor separation barrel, one end of another main guide pipe (10) is inserted into a port C (16) of the water-vapor separation barrel, the other end of another main guide pipe (10) is connected with a vacuum pump (9), a rubber sealing ring (13) is used for sealing between the main guide pipe (10) connected with the branch guide pipe (11) and the top of the port A (14) of the water-vapor separation barrel, and a rubber sealing ring (13) is used for sealing between the other main guide pipe (10) and the top of the port C (16) of the water-vapor separation barrel; and in the vacuum process, a valve of a port B (15) of the water-vapor separation barrel is opened intermittently, and the liquid in the water-vapor separation barrel (12) is discharged.
9. The method of claim 6, wherein the method comprises the steps of: in the step S1, the distance between two adjacent bamboo poles (1) implanted in the soft soil is 3D-8D, and D is the outer diameter of the bamboo pole (1).
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| CN202110608816.2A CN113309070A (en) | 2021-06-01 | 2021-06-01 | Drainage moso bamboo for soft soil foundation treatment and construction method thereof |
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