阅读说明：本技术 一种沿海软土地基水泥土复合搅拌桩成桩方法 (Method for forming coastal soft soil foundation cement soil composite mixing pile ) 是由 成诗冰 陈军 熊宏武 廖峰 王海军 王首斌 杨海 康滔滔 熊宇鹏 张叶 夏冰 于 2021-09-09 设计创作，主要内容包括：本发明公开了一种沿海软土地基水泥土复合搅拌桩成桩方法,包括：平整场地,桩机定位、对中、调平；启动深层搅拌桩机,并按照设定速度下沉；深层搅拌桩机预搅下沉同时,后台将相应份量的主料、辅料与水充分混合搅拌均匀,得水泥浆液；桩机下沉到达设计深度后,开启浆液泵,将浆液泵送至搅拌头的出浆口,出浆后启动搅拌桩机及拉紧链条装置,按设计确定的提升速度边喷浆搅拌边提升桩机的钻杆,使浆液和土体充分拌和；施工完一根桩后,移动桩机至下一根桩位,重复以上步骤直至场地内全部搅拌桩施工完成。该方法通过有效提高水泥颗粒的分散性,加快水泥水化速度,提高水泥水化程度,从而提高并保障搅拌桩的成桩质量。(The invention discloses a coastal soft soil foundation cement soil composite mixing pile forming method, which comprises the following steps: leveling a field, positioning, centering and leveling a pile machine; starting a deep mixing pile machine, and sinking at a set speed; while the deep mixing pile machine is pre-stirred and sinks, the main material and the auxiliary material with corresponding weight are fully mixed and uniformly stirred with water in the background to obtain cement slurry; after the pile machine sinks to reach the designed depth, a slurry pump is started, slurry is pumped to a slurry outlet of a stirring head, the stirring pile machine and a tensioning chain device are started after slurry is discharged, a drill rod of the pile machine is lifted while slurry spraying and stirring are carried out according to the lifting speed determined by design, and the slurry and a soil body are fully mixed; and after one pile is constructed, moving the pile machine to the next pile position, and repeating the steps until the construction of all the mixing piles in the site is completed. The method can accelerate the hydration speed of the cement and improve the hydration degree of the cement by effectively improving the dispersibility of the cement particles, thereby improving and ensuring the pile forming quality of the mixing pile.)

1. A coastal soft soil foundation cement soil composite mixing pile forming method is characterized by comprising the following steps:

leveling a field, positioning, centering and leveling a pile machine;

step two, starting the deep mixing pile machine, and sinking at a set speed;

step three, pre-stirring and sinking the deep mixing pile machine, and fully mixing and uniformly stirring the main materials and the auxiliary materials with corresponding parts with water by the background to obtain cement slurry, wherein the main materials comprise cement, lime and an excitant, and the auxiliary materials comprise silicon powder, sea sand, slag and fly ash;

step four, after the pile machine sinks to reach the designed depth, a slurry pump is started, cement slurry is pumped to a slurry outlet of the stirring head, the stirring pile machine and the tensioning chain device are started after slurry is discharged, and a drill rod of the pile machine is lifted while slurry is sprayed and stirred according to the lifting speed determined by design, so that the slurry and the soil body are fully mixed;

step five, after one pile is constructed, moving the pile machine to the next pile position, and repeating the steps until all the mixing piles in the field are constructed;

the blended amount of the main material is 8-16% of the mass of the soft soil to be reinforced, the blended amount of the auxiliary material is 45-55% of the mass of the soft soil to be reinforced, the blended amount of the cement is 40-65% of the mass of the main material, the blended amount of the lime is 25-45% of the mass of the main material, the blended amount of the excitant is 3.5-8% of the mass of the main material, the blended amount of the silica powder is 10-15% of the mass of the auxiliary material, the blended amount of the sea sand is 32-54.5% of the mass of the auxiliary material, the blended amount of the slag is 15-28% of the mass of the auxiliary material, and the blended amount of the fly ash is 20-36% of the mass of the auxiliary material.

2. The pile-forming method of claim 1, wherein: the cement is ordinary portland cement of PO42.5 grade.

3. The pile-forming method of claim 1, wherein: the excitant is sodium silicate or sulfate.

4. The pile-forming method of claim 1, wherein: the mass of the SiO2 in the silicon powder accounts for 85-90%, and the particle diameter of the silicon powder is 80-120 meshes.

5. The pile-forming method of claim 1, wherein: the particle size of the sea sand is less than or equal to 1 mm.

6. The pile-forming method of claim 1, wherein: the grade of the slag is greater than S95 grade.

7. The pile-forming method of claim 1, wherein: the fly ash is class F I I grade fly ash.

8. The pile-forming method of claim 1, wherein: in the fourth step, the drill rod needs to be repeatedly lifted and sunk for 2-4 times in the stirring process.

9. The pile-forming method of claim 1, wherein: the lifting speed in the fourth step is 0.50-0.8 m/min.

10. The pile-forming method of claim 1, wherein: and in the second step, the sinking speed of the deep mixing pile machine is 0.35-0.75 m/min.

Technical Field

The invention belongs to the technical field of civil engineering, and particularly relates to a coastal soft soil foundation cement soil composite mixing pile forming method.

Background

China is wide in territory and complex in geological conditions, and many urban foundation constructions often encounter soft soil foundations. The water content of the soft soil is higher than the liquid limit, and the pore ratio is more than 1, so the compressibility of the soft soil is higher, and the bearing capacity is not ideal. Because the bearing capacity is extremely low, the engineering geological condition is poor, and greater settlement or deformation can be generated in the engineering, which causes great harm to the roadbed construction, technical means such as cement soil composite mixing piles and the like are often adopted for processing to reach the engineering geological requirement, but the mixing piles constructed by the existing pile forming method still have the technical problem of insufficient bearing capacity.

In view of the above, there is a need for improvements in the prior art.

Disclosure of Invention

The invention mainly aims to provide a method for forming a coastal soft soil foundation cement soil composite mixing pile, aiming at effectively improving the dispersibility of cement particles, accelerating the hydration speed of cement and improving the hydration degree of cement, thereby improving and ensuring the pile forming quality of the mixing pile.

Therefore, the method for forming the coastal soft soil foundation cement soil composite mixing pile provided by the embodiment of the invention comprises the following steps:

leveling a field, positioning, centering and leveling a pile machine;

step two, starting the deep mixing pile machine, and sinking at a set speed;

step three, pre-stirring and sinking the deep mixing pile machine, and fully mixing and uniformly stirring the main materials and the auxiliary materials with corresponding parts with water by the background to obtain cement slurry, wherein the main materials comprise cement, lime and an excitant, and the auxiliary materials comprise silicon powder, sea sand, slag and fly ash;

step four, after the pile machine sinks to reach the designed depth, starting a slurry pump, pumping slurry to a slurry outlet of the stirring head, starting the stirring pile machine and a chain tensioning device after slurry is discharged, and lifting a drill rod of the pile machine while spraying and stirring according to the lifting speed determined by design so as to fully mix the slurry and the soil body;

step five, after one pile is constructed, moving the pile machine to the next pile position, and repeating the steps until all the mixing piles in the field are constructed;

the blended amount of the main material is 8-16% of the mass of the soft soil to be reinforced, the blended amount of the auxiliary material is 45-55% of the mass of the soft soil to be reinforced, the blended amount of the cement is 40-65% of the mass of the main material, the blended amount of the lime is 25-45% of the mass of the main material, the blended amount of the excitant is 3.5-8% of the mass of the main material, the blended amount of the silica powder is 10-15% of the mass of the auxiliary material, the blended amount of the sea sand is 32-54.5% of the mass of the auxiliary material, the blended amount of the slag is 15-28% of the mass of the auxiliary material, and the blended amount of the fly ash is 20-36% of the mass of the auxiliary material.

Specifically, the cement is ordinary portland cement of PO42.5 grade.

Specifically, the excitant is sodium silicate or sulfate.

Specifically, the particle diameter of the silicon powder is 80-120 meshes.

Specifically, the particle size of the sea sand is less than or equal to 1 mm.

Specifically, the grade of the slag is greater than the grade of S95.

Specifically, the fly ash is F-class II-grade fly ash.

Specifically, in the stirring process in the fourth step, the drill rod needs to be repeatedly lifted and sunk for 2-4 times.

Specifically, the lifting speed in the fourth step is 0.50-0.8 m/min.

Specifically, the content of CaO + MgO in the lime is not less than 80%.

Specifically, in the second step, the sinking speed of the deep mixing pile machine is 0.35-0.75 m/min.

At least one embodiment of the invention has the following beneficial effects: the invention fully utilizes sea sand to reduce river sand resource exploitation, utilizes slag to improve the quality of silt clay, and because the main components of alkaline residue are calcium salts such as calcium carbonate, calcium sulfate, calcium chloride and the like, hydrated calcium carbonate, hydrated calcium aluminosilicate and the like are generated after hydration reaction, and the hydrated products not only can effectively fill the pores of the soil body, but also have strong physical cementation capability, can well connect soil particles, and can effectively improve the quality of clay. Meanwhile, through the precise cooperative control of the components, the problems of difficult pile forming and poor pile forming quality of the mixing pile in coastal areas are solved, the integrity of the pile body of the prepared cement soil composite mixing pile is better, and the strength is improved by about 35 percent compared with that of the conventional cement mixing pile.

Detailed Description

The present invention will be further described with reference to the following embodiments.

The soil and muddy clay foundation with physical parameters shown in the table 1 is reinforced.

TABLE 1 basic physical indexes of mucky clay and silty clay in the Zhuhai Hongwan logistic park area

Example 1

A coastal soft soil foundation cement soil composite mixing pile forming method comprises the following steps:

leveling a field, positioning, centering and leveling a pile machine, and adjusting the verticality of a guide frame, wherein the verticality is less than 1.0% of the pile length;

step two, starting a deep mixing pile machine, and sinking at the speed of 0.35-0.75 m/min;

step three, pre-stirring and sinking the deep mixing pile machine, fully mixing and uniformly stirring the main materials, the auxiliary materials and water in corresponding parts by a background to obtain cement slurry, wherein the main materials comprise PO 42.5-grade ordinary portland cement, lime and an exciting agent, the auxiliary materials comprise silica powder with the particle size of 80-120 meshes, sea sand with the particle size of less than or equal to 1mm, slag with the grade of more than S95 and F-class II-grade fly ash, the content of CaO and MgO in the lime is not less than 80%, the mass of SiO2 in the silica powder accounts for 85% -90%, and the exciting agent is sodium silicate or sulfate;

fourthly, after the pile machine sinks to reach the designed depth, starting a slurry pump, pumping slurry to a slurry outlet of the stirring head, starting the stirring pile machine and a tensioning chain device after slurry is discharged, lifting a drill rod of the pile machine while spraying and stirring according to the lifting speed (0.50-0.8 m/min) determined by design, fully stirring the slurry and a soil body, repeatedly lifting, stirring and sinking for 2-4 times, ensuring that the slurry is fully contacted with a soft soil body, and ensuring the quality of the stirring pile;

step five, after one pile is constructed, moving the pile machine to the next pile position, and repeating the steps until all the mixing piles in the field are constructed;

wherein, the main material is 16% of the soft soil mass to be reinforced, and the auxiliary material is 45% of the soft soil mass to be reinforced, wherein: the mixing amount of the cement is 60% of the mass of the main material, the mixing amount of the lime is 35% of the mass of the main material, the mixing amount of the excitant is 5% of the mass of the main material, the mixing amount of the silicon powder is 10% of the mass of the auxiliary material, the mixing amount of the sea sand is 50% of the mass of the auxiliary material, the mixing amount of the slag is 25% of the mass of the auxiliary material, and the mixing amount of the fly ash is 15% of the mass of the auxiliary material. The components of the curing material in the proportion are fully and uniformly mixed, water is added for uniform stirring, and after the stirring pile is solidified, a core is drilled, and the unconfined compressive strength of the core is measured, namely the unconfined compressive strength of the core is measured at 7d, 14d and 28d, as shown in table 2.

Example 2

Different from the embodiment 1, the main material is 12% of the mass of the soft soil to be reinforced, and the auxiliary material is 50% of the mass of the soft soil to be reinforced, wherein: the mixing amount of the cement is 45% of the mass of the main material, the mixing amount of the lime is 50% of the mass of the main material, the mixing amount of the excitant is 5% of the mass of the main material, the mixing amount of the silicon powder is 10% of the mass of the auxiliary material, the mixing amount of the sea sand is 45% of the mass of the auxiliary material, the mixing amount of the slag is 25% of the mass of the auxiliary material, and the mixing amount of the fly ash is 20% of the mass of the auxiliary material. The components of the curing material in the proportion are fully and uniformly mixed, water is added for uniform stirring, and after the stirring pile is solidified, a core is drilled, and the unconfined compressive strength of the core is measured, namely the unconfined compressive strength of the core is measured at 7d, 14d and 28d, as shown in table 2.

Example 3

Different from the embodiment 1, the main material accounts for 8% of the mass of the soft soil to be reinforced, the auxiliary material accounts for 55% of the mass of the soft soil to be reinforced, the cement mixing amount accounts for 50% of the mass of the main material, the lime mixing amount accounts for 45% of the mass of the main material, the excitant mixing amount accounts for 5% of the mass of the main material, the silica powder mixing amount accounts for 10% of the mass of the auxiliary material, the sea sand mixing amount accounts for 40% of the mass of the auxiliary material, the slag mixing amount accounts for 25% of the mass of the auxiliary material, and the fly ash mixing amount accounts for 25% of the mass of the auxiliary material. The components of the curing material in the proportion are fully and uniformly mixed, water is added for uniform stirring, and after the stirring pile is solidified, a core is drilled, and the unconfined compressive strength of the core is measured, namely the unconfined compressive strength of the core is measured at 7d, 14d and 28d, as shown in table 2.

Comparative example 1

Different from the embodiment 1, the main material accounts for 8% of the mass of the soft soil to be reinforced, the auxiliary material accounts for 60% of the mass of the soft soil to be reinforced, the cement mixing amount accounts for 60% of the mass of the main material, the lime mixing amount accounts for 35% of the mass of the main material, the excitant mixing amount accounts for 5% of the mass of the main material, the silica powder mixing amount accounts for 15% of the mass of the auxiliary material, the sea sand mixing amount accounts for 35% of the mass of the auxiliary material, the slag mixing amount accounts for 25% of the mass of the auxiliary material, and the fly ash mixing amount accounts for 25% of the mass of the auxiliary material. The components of the curing material in the proportion are fully and uniformly mixed, water is added for uniform stirring, and after the stirring pile is solidified, a core is drilled, and the unconfined compressive strength of the core is measured, namely the unconfined compressive strength of the core is measured at 7d, 14d and 28d, as shown in table 2.

Comparative example 2

Different from the embodiment 1, the main material is 12% of the mass of the soft soil to be reinforced, the auxiliary material is 40% of the mass of the soft soil to be reinforced, the cement mixing amount is 45% of the mass of the main material, the lime mixing amount is 50% of the mass of the main material, the excitant mixing amount is 5% of the mass of the main material, the silica powder mixing amount is 15% of the mass of the auxiliary material, the sea sand mixing amount is 35% of the mass of the auxiliary material, the slag mixing amount is 20% of the mass of the auxiliary material, and the fly ash mixing amount is 30% of the mass of the auxiliary material. The components of the curing material in the proportion are fully and uniformly mixed, water is added for uniform stirring, and after the stirring pile is solidified, a core is drilled, and the unconfined compressive strength of the core is measured, namely the unconfined compressive strength of the core is measured at 7d, 14d and 28d, as shown in table 2.

Comparative example 3

Different from the embodiment 1, the main material accounts for 8% of the mass of the soft soil to be reinforced, the auxiliary material accounts for 40% of the mass of the soft soil to be reinforced, the cement mixing amount accounts for 60% of the mass of the main material, the lime mixing amount accounts for 35% of the mass of the main material, the excitant mixing amount accounts for 5% of the mass of the main material, the silica powder mixing amount accounts for 10% of the mass of the auxiliary material, the sea sand mixing amount accounts for 40% of the mass of the auxiliary material, the slag mixing amount accounts for 25% of the mass of the auxiliary material, and the fly ash mixing amount accounts for 25% of the mass of the auxiliary material. The components of the curing material in the proportion are fully and uniformly mixed, water is added for uniform stirring, and after the stirring pile is solidified, a core is drilled, and the unconfined compressive strength of the core is measured, namely the unconfined compressive strength of the core is measured at 7d, 14d and 28d, as shown in table 2.

TABLE 2 compressive Strength test results (MPa)

From the data of the three examples, the compressive strength of the three time periods in the examples 1 to 3 is higher than the design requirement, and the compressive strength of the 7d in the comparative examples 1 to 3 is lower than the requirement of 0.70MPa, which shows that the fly ash and the silica powder in the proportion well play the role of the micro-aggregate, effectively improve the dispersibility of cement particles, accelerate the hydration speed of the cement, improve the hydration degree of the cement, fully utilize the sea sand to reduce the exploitation of river sand resources, effectively reduce the cost and save the resources.

The above examples are merely illustrative for clearly illustrating the present invention and are not intended to limit the embodiments. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. Nor is it intended to be exhaustive of all embodiments. And obvious variations or modifications of the invention may be made without departing from the scope of the invention.