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Selection of precast pile drill pipe drilling or cast-in-place pile drill pipe drilling multi-directional analysis
Release time:
2021-08-25
Author:
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According to different construction methods, piles can be divided into prefabricated piles (prestressed pipe piles) and cast-in-place piles (cast-in-place drill pipe piles). Both are widely used in soft soil foundation and deep buried foundation, which have the characteristics of high bearing capacity, good stability, small settlement and low material consumption, which can effectively meet the requirements of building for foundation strength, deformation and stability. The two types of piles have their own characteristics, different construction methods, different mechanical equipment and construction techniques, different mechanisms of pile and soil, and different scope of application. This article will compare these two types of piles, analyze their advantages and disadvantages and applicability, so as to determine whether to choose prestressed pipe piles or bored piles
According to different construction methods, piles can be divided into precast piles (prestressed pipe piles) and cast-in-place piles (drill pipecast-in-place pile). Both are widely used in soft soil foundation and deep buried foundation, which have the characteristics of high bearing capacity, good stability, small settlement and low material consumption, which can effectively meet the requirements of building for foundation strength, deformation and stability. The two types of piles have their own characteristics, different construction methods, different mechanical equipment and construction techniques, different mechanisms of pile and soil, and different scope of application. This article will compare these two types of piles, analyze their advantages and disadvantages and applicability, so as to determine whether to choose prestressed pipe piles or bored piles.
Prestressed pipe pile is a kind of slender concrete precast member of hollow pipe body made by pre-tensioning technology, adding high-efficiency water reducing agent, high-speed centrifugal steam curing molding method, mainly composed of cylindrical pile body, end plate and steel sleeve hoop..
The bored pile is a pile made by using a drilling rig to drill holes in the soil at the engineering site, excavating the slag hole on one side of the broken soil, and then placing the steel skeleton in the pile hole, and then pouring concrete.
The prestressed pipe pile and bored pile are compared and analyzed from the angle of action mechanism, construction condition, construction technology and construction cost.
From the perspective of mechanism
Prestressed pipe pile is into or through the drill pipe pressure into the foundation to reach the required depth, in the process of the pile, the pile around the surrounding soil is squeezed out, in the short term caused by pore water pressure, uplift and lateral extrusion of the soil, the stress will affect the scope of the existing buildings, road content and deformation, and even damage. At the same time, it will also squeeze the finished building pile, causing it to drift and float.
Drill pipe bored pile shall be drilled by dry method or mud retaining method. In the process of forming holes and piles, there is no squeezing effect on the soil between the surrounding piles, which will not cause the increase of excessive pore water pressure in the soil. Therefore, the construction of piles will not endanger the safety of adjacent buildings and roads. Therefore, compared with the prestressed pipe pile, the bored pile has the characteristics of no vibration, no compaction effect, and little influence on the surrounding buildings, but the concrete strength of the pile body is lower, the bearing capacity of the single pile is lower, and the settlement is larger.
From the construction conditions
The prestressed pipe pile is suitable for soft soil, sandy soil, plastic soil, silty soil, fine sand and loose gravel soil without boulders or floats. It does not easily penetrate into thick sand and other hard interlayers, and can only enter to the depth of sand, gravel, hard clay, strongly weathered rock and other solid supporting layers. When it is difficult to drive piles in sand layer, boulder, etc., pilot hole measures can be adopted. When driving or static pressure prestressed pipe pile, and using strong weathered rock as the pile foundation support layer, the pile body will pass through most of the weak soil, cohesive soil and weathered rock layer, so there will be no resistance to the pile body in general. Such as local leaching and the distribution of solitary stones throughout the clastic rocks may cause some difficulties in the formation of piles. Because the construction needs to have vibration pile hammer, lifting equipment and other large machinery, so the construction site required is larger.
Drill-stem cast-in-place piles are suitable for a variety of sandy and cohesive soils, as well as gravel and cobblestone soils and rock formations. However, it is difficult to construct silt and foundations that may have flowing sand or confined water. Therefore, compared with the prestressed pipe pile, the bored pile has the characteristics of simple construction equipment, convenient operation, and no site restriction, but the construction period is longer than the prestressed pipe pile, and the construction quality is unstable.
From the point of view of construction technology
The construction technology of prestressed pipe pile is as follows: measurement and positioning → placement and centering of pile driver → pile pressing → pile adding → pile feeding or cutting → static pressure pile reaching the design elevation.
(1) Measurement and positioning: Place the shaft and piles before construction, and paint to make the signs obvious.
(2) Placement and centering of pile driver: pile driver is used to start theodolite
Key words:
Drill pipe, construction, prestressed, soil, borehole, therefore, different, with, buildings, characteristics
