Try to compare the advantages and disadvantages of precast piles and grouted piles?

Precast piles are factory produced, the cost is greatly reduced; the reinforcement rate is very small, which greatly saves steel; hollow piles are very environmentally friendly; the diameter is small and the specific surface area is large; the bearing capacity of a single party of concrete is very large; the construction is simple and the technical difficulty is low.

The crowding effect of precast piles is negative in saturated cohesive soil, which will lead to quality accidents such as broken piles and necking of cast piles. For crowding precast concrete piles and steel piles, it will lead to floating of piles, lowering of bearing capacity and increasing of settlement; crowding effect will also cause damage to neighboring houses and municipal facilities; in loose soil and unsaturated fill, it is positive, which will play a role in encrypting and increasing of bearing capacity.

For non-extruded piles, because there is no negative effect of soil crowding, but also has the ability to pass through all kinds of hard interlayers, embedded rock and enter all kinds of hard holding layer, the geometry of the pile and the bearing capacity of a single pile can be adjusted in a large space. Therefore, the drilled and bored piles can be used in a wide range, especially for high and heavy buildings.

Grouted piles are directly drilled in the designed pile position, and then reinforced cages are placed inside the holes, and then concrete is poured into them. However, these piles have the outstanding problem that the slag (virtual soil) at the bottom of the pile cannot be cleaned up, thus restricting its bearing capacity and the stability of the project quality. In order to solve this problem, the construction process of pressure grouting at the bottom of bored piles was invented in the late 1990s. The process can be broadly categorized into four types: ?

(1) pre-buried grouting and overflow pipe after drilling, after pouring the pile concrete, the cement slurry is directly injected into the soil at the bottom of the pile, and the slurry is mixed and solidified into a high-strength "mixture" with the slag at the bottom of the pile and the soil around the bottom of the pile, i.e., the so-called open type grouting.

(2) After drilling, pre-buried pipe and pouring pile, the cement slurry is injected into the prefabricated elastic cavity at the bottom of the pile, with the increase of grouting pressure and slurry volume, the elastic cavity gradually expands and expands, and forms a high-strength "combination" in the soil layer under the pile, which is known as closed type grouting.

(3) After digging the hole manually and pre-burying the conduit, after pouring the concrete of the pile body, the drilling rig will drill along the conduit into the soil at the end of the pile and then grout the pile, which is also applicable to the pile foundation when there is a defect that needs to be dealt with.

(4) Grouting and vibration immediately after drilling, and finally pouring pile body concrete.?

Which the first, second and third process is more applied, and the effect is also more significant.?

2?Advantages of pile bottom grouting piles?

The advantages of pile bottom grouting are mainly reflected in the following aspects:?

(1) It inherits all the advantages of ordinary grouted piles, such as applicable to various geological conditions, no vibration damage, no noise, etc.

(2) The advantages of grouted piles are as follows.

(2) Creatively put forward and realized the construction process of pile bottom pressure grouting, which makes the single pile bearing capacity increase at least 20% or even more than 100% compared with the ordinary grouted pile of the same diameter and length. Therefore, it greatly shortens the design length of the pile, reduces the construction cost, and the economic benefit is very obvious.

(3) The settlement is greatly reduced, which is suitable for industrial buildings and machinery and equipment foundations, etc. where the superstructure is sensitive to settlement.?

(4) The pressure grouting on the pile side not only makes the mud skin and soil on the pile side to be mixed and squeezed, but also makes the soil and the concrete of the pile body to be linked into a whole, and the hardened stones of the slurry will also form a wedge on the pile side. All these will make the friction area between the pile and the soil increase and improve the lateral friction resistance. This advantage can be more widely used in the design of resistant piles.