《高压喷射灌浆和深层搅拌法加固技术（Reinforcement technique of high pressure jet grouting and deep mixing method）.doc》由会员分享，可在线阅读，更多相关《高压喷射灌浆和深层搅拌法加固技术（Reinforcement technique of high pressure jet grouting and deep mixing method）.doc（12页珍藏版）》请在三一文库上搜索。
1、高压喷射灌浆和深层搅拌法加固技 术（Reinforcement technique of high pressure jet grouting and deep mixing method）Reinforcement technique of high pressure jet grouting and deep mixing method-Abstract: the technology of high pressure jet grouting and deep mixing is similar. The main difference is that different feeding
2、 and mixing methods are adopted.Key words: high pressure jet grouting; deep mixing; strengtheningFirst, high pressure jet grouting technologyHigh pressure injection method is the use of engineering drilling to design processing depth, high pressure mud pump, through the installation of the drill pip
3、e (spray rod rod) special nozzle arranged at the end of the bottom of the hole, jet cement slurry to surrounding soil pressure (general use cement), and the drill pipe (boom) rotate at a certain speed the soil structure upgrade, high pressure jet within a certain range of damage, and forced mixing a
4、nd curing slurry solidification after the formation of a solid with certain properties and shape in soil.The shape of the consolidated body is related to the direction of the jet flow. Generally divided into rotary jet (referred to as rotary jet), directional jet (referred to as fixed jet) and oscil
5、lating jet (referred to as pendulum spray). The jet grouting pile is mainly used to reinforce the foundation, improve the shear strength of the foundation, and improve the deformation property of the foundation soil, so that it can not destroy or produce too big deformation under the action of the u
6、pper structure. Jet consolidation body is wall shaped, fan-shaped jet formation consolidation thick body. Constant injection and pendulum spraying are usually used to prevent seepage of foundation and improve hydraulic condition and slope stability of foundation soil.(1) reinforcement mechanismHigh
7、pressure compressed air parcel damage with high impact jet flow stirring soil spray method such as three high and low pressure spray method, grouting slurry is poured into the slurry pump, high pressure water and air entrainment into, and disturbed soil mixed consolidated. The mechanism of reinforci
8、ng the foundation to form piles, plates and walls can be explained by five functions:1. high pressure jet cutting destroys the soil, and the dynamic pressure of the jet impacts the soil in pulse form, and the structure of the soil is destroyed and the cavity appears.2. mixing effect in the process o
9、f rotation and lifting the drill pipe, the formation of voids in the jet back in the injection pressure, forcing the soil particles and nozzle moving in opposite directions (i.e. small resistance direction) mobile, consolidated and mixed slurry.3. replacement three pipe high pressure jet method call
10、ed displacement method, high speed water jet cutting soil at the same time, due to pass into the compressed air and the part of cutting soil particles from the grouting hole, the soil particles discharged by the air volume by pouring slurry feeding.4. filling and consolidation effect of the high pre
11、ssure grout filling open and original soil void, condensate water consolidation, but also penetrate into the sand thickness and the formation of consolidation.5. the compacting effect of high pressure jet flow in the process of cutting soil, in the edge and the residual pressure is broken, and the p
12、ressure can have a certain effect on soil compaction, the high compressive strength of pile body is higher than the edge portion of the central part.(two) basic speciesAccording to the injection medium and its piping number, it can be divided into single tube method, two tube method, three tube meth
13、od, etc.1. single tube jet grouting through a single pipeline, the use of high-pressure slurry (20 30MPa), jet punching cut soil destruction, the pile diameter of 40 50cm. The utility model has the advantages of good reinforcement quality, fast construction speed and low cost, but the diameter of th
14、e consolidation body is smaller.2., two tube spinning method, in the single tube method on the basis of compressed air, and the use of double channel double grouting pipe. There is a coaxial double nozzle at the bottom side of the tube. The high-pressure slurry is ejected at a pressure of about 20MP
15、a from the inner nozzle at high speed, and the compressed air around 0.7MPa is ejected at the periphery of the jet. In the soil, a column shaped consolidation body with obvious diameter increases, ranging from 80 to 150cm.3., three tube jet grouting using three kinds of medium, respectively, conveyi
16、ng water, gas and slurry three grouting pipes. Coaxial flow of high pressure water jet and jet surrounded by punching failure in the surrounding soil, a high-pressure water jet nozzle and the cylindrical air jet, water, gas coaxial jet, can reduce the friction of water jet and the surrounding medium
17、, avoid water flowing through early atomization, enhanced water jet cutting ability. The nozzle side rotary jet, lifting, negative pressure area is formed larger in the foundation, carrying the slurry filling gap at the same time pressed, it will form a large diameter, high strength consolidation in
18、 the foundation, the foundation reinforcement effect.(three) slurry materialCement is the basic material of jet grouting, and cement grout can be divided into the following types.1. ordinary portland cement slurry is generally used, without any admixture, the water cement ratio is generally 0.8:1 1.
19、5:1, the compressive strength of solidified body (28d) up to 1 20MPa, suitable for no special requirements of the project.2. - speed - early - strength type is suitable for the project with higher water level or early load. The compressive strength of cement soil consolidated with 2% calcium chlorid
20、e is 1.6MPa, and after adding 4% CaCl2, the compressive strength is 2.4MPa.ThreeThe average compressive strength of high strength jet consolidated body is above 20MPa. High grade cement can be selected, or a composite formulation consisting of highly effective diffusion agents and inorganic salts ca
21、n be selected.2 - 4% water glass is added to cement slurry, and its impermeability is improved obviously. If the project is impervious, it is better to use flexible materials. The cement slurry can be filled with 10 50% bentonite (the proportion of the cement weight). This is the use of slag cement,
22、 such as the only anti permeability requirements without freezing all can use the volcano ash cement.(four) high pressure jet grouting process;The range of injection shall be determined by field test. There is a close relationship between the size of the high jet consolidated body and the type of so
23、il and its compactness. The size of the consolidated body formed by different injection types and injection modes is also different. The injection energy of fixed injection is concentrated, and the range of injection is larger. See table 5-6.Table 5-6 characteristics of high pressure jet grouting co
24、nsolidation bodyCharacteristics of consolidation bodySprinkling irrigation methodSingle tube methodTwo tube methodThree tube methodEffective diameter of consolidation body (m)cohesive soil0N101.2 + 0.21.4 + 0.32 + 0.310N200.8 + 0.21.1 + 0.31.5 + 0.320N300.6 + 0.20.8 + 0.31 + 0.3Sand soil0N101 + 0.21
25、.6 + 0.32.5 + 0.310N200.8 + 0.21.3 + 0.31.8 + 0.320N300.6 + 0.21 + 0.31.2 + 0.3Gravel sand20N300.6 + 0.21 + 0.31.2 + 0.3Effective length of unidirectional injection (m)1 to 2.5Single pile vertical limit load (kN)50060010001200Two thousandHorizontal ultimate load (kN) of single pile3040Maximum compre
26、ssive strength (MPa)Sandy soil 1020, cohesive soil 26, gravel sand 820Average flexural strength / average compressive strength1/5 to 1/10Dry soil bulk density (kN/m3)Sandy soil 1620, clayey soil 1415, loess 135Coefficient of permeability (cm/s)Sandy soil and gravel are from 10-5 to 10-7 and cohesive
27、 soil is 10-6 10-7Cohesive force (MPa)Sandy soil 0.4 0.5, cohesive soil 0.7 1Internal friction angle phi (o)Sandy soil 3040, cohesive soil 2030Standard penetration hammer number NSandy soil 3050, cohesive soil 2030Elastic wave (km/s)P waveSandy soil 23, cohesive soil 1.5 2S waveSandy soil 1 1.5, coh
28、esive soil 0.8 1The consolidation strength of rotary jet cohesive soil is 0.3 6.0MPa, and the consolidation strength of cohesionless soil is 4 15MPa.For seepage control works, regular injection and pendulum spraying are adopted. When the size of the formation is coarse, the pendulum or jet grouting
29、is adopted. For the complex formation with a depth of more than 20m, it is better to make the high injection pile form a water shutoff curtain by double or three rows of holes. The hole distance should be 1.73R (R is the radius of the rotary jet consolidation body), the most economical when the row
30、spacing is 1.5R. General fixed injection, swing jet hole distance from 1.2 to 2.5m, spin jet is 0.8 1.2m. The effect of high permeability can reach up to 10-5 10-6cm/s.The distance of high injection piles should be determined according to the load of the superstructure, the bearing capacity of the s
31、ingle pile and the soil condition. Generally, the distance between piles is S = (34) d (D is the diameter of the churning pile), and the layout of the piles may be rectangular or quincunx.Construction of high pressure jet grouting drilling to the grouting pipe is inserted into the predetermined soil
32、, from the bottom to the top of the spray machine. Recently, the method of vibroflotation has also been used to form holes directly for spraying operations. The following items should be paid attention to when spraying:(1) when grouting depth is large, it is easy to form a consolidation body with up
33、per, lower and lower thickness, which affects the bearing capacity or impermeability of consolidated body. Therefore, measures such as increasing the pressure and flow rate or reducing the speed of rotation and lifting are needed;(2) when the amount of shotcrete is not enough to influence the qualit
34、y of the project, the double jet technology can be adopted;(3) when the amount of slurry is more than 20% of the grouting amount, measures such as increasing the injection pressure, reducing the diameter of the nozzle, speeding up the hoisting speed and rotating speed can be adopted, and the slurry
35、can be recovered and utilized;(4) according to the project needs to adjust the injection pressure and grouting amount, changing the nozzle moving direction and speed control of spray concretion body shape, namely disk, cylindrical, bottom shape, sugar paste, reed shaped cap and wall.(5) after irriga
36、tion, the slurry has a phenomenon of water separation, which can lead to the depression at the top of the consolidation body, which is unfavorable to the foundation reinforcement and seepage control. Therefore, static pressure grouting or adding expansion material in slurry can be adopted to prevent it.High pressure pump is the key equipment in high pressure jet grouting, and the pressure and flow rate can be adjusted in a certain range. Rated flow is 85 150L/min; rated pressure is 20 50MPa.Table 5-7 jet grouting parameter listTypes of high injection groutingSingle tube method