Immersed tube prefabricated multistage under-reamed pile

Abstract

The invention relates to an immersed tube prefabricated steel concrete expanded bottom pile, in particular to an immersed tube prefabricated multi-stage expanded bottom pile, which is the first choice expanded bottom pile in foundation engineering of high-rise buildings, and is also applicable to any other foundation soil quality and safety level application in construction. It consists of a pile body and a cast-in-place concrete base located in a hard soil layer, wherein the pile body is composed of at least two sections, and a cast-in-place concrete base is arranged between them, and through their respective upper and lower bars The cast-in-place concrete base is anchored and connected into a whole. The invention significantly improves the bearing capacity of the single pile and the utilization rate of the material strength, easily achieves the expected effect of the design, and better meets the needs of construction projects. At the same time, it has a wide application range, regardless of high-rise or low-rise buildings, safety levels and foundation soil conditions. It can be combined into prefabricated multi-stage bottom expansion piles with immersed tubes that match it.

Description

Technical field [0001] The present invention relates to an immersed tube prefabricated steel concrete expanded bottom pile, in particular to an immersed tube prefabricated multi-stage expanded bottom pile, which is the preferred expanded bottom pile in the foundation engineering of high-rise buildings, and is also applicable to any other foundation soil quality and safety level application in construction. Background technique [0002] At present, in the pile foundation engineering of the foundation, three kinds of cast-in-situ piles, prefabricated piles and large-diameter bored piles are usually used. Among them, the large-diameter bored pile has the highest bearing capacity, but it is expensive, low in work efficiency, and seriously polluted during construction, so it is only used in high-rise buildings and buildings with high bearing capacity requirements. Prefabricated piles have good quality and high bearing capacity, but their cost is also high, and they are generally...

AI Technical Summary

Problems solved by technology

Among them, the most widely used is the immersed tube pouring pile, which accounts for about 50% of the total number of various piles. The pile body of the pile is cast-in-situ steel concrete, and the pile head is prefabricated; The head is buried in the hard soil layer of the foundation, and then poured into piles; but due to the different ages of the soil formed by the crust, the soft soil foundation usually has an alternating state of soft and hard soil layers with the increase of the depth of the crust, so that in continuous piling construction When piles are installed later, the soil layer will be squeezed, which will affect the piles that have been poured before and have not been completely solidified, especially at the junction of the soft soil layer and the hard soil layer, often resulting in broken piles, shrinkage, etc. As a result, the quality of about 10-20% of the cast-in-place piles cannot meet the requirements, forcing designers to lower the standard of single pile bearing capacity, resulting in dense piles, causing serious deformation of the soil, and even endangering the integrity of the pile body. Quality; Another shortcoming of this pile is that its bearing capacity is low. In order to increase the bearing capacity, the method of pressurizing and expanding the bottom behind the concrete pouring pile is generally adopted, but because of the use of pressurized and expanding the bottom, the shape and size are uncertain and Standards make its application limited. Based on the above reasons, the patent No. ZL97105261.1 discloses a variety of immersed tube prefabricated steel concrete expanded bottom piles, which better solve the defects existing in the foundation piles in the past. The end diameter can usually reach 1.5-1.7 meters, and the expanded bottom area can reach 2.3 square meters, which limits the base diameter to the above-mentioned range. If the base diameter is too large to increase the bearing capacity of the single pile, it will not only increase the difficulty of construction, Moreover, it will have an adverse effect on the performance of its end bearing capacity, resulting in a greatly reduced calibrated bearing capacity. That is to say, the potential for increasing the bearing capacity of a single pile by enlarging the diameter of the foundation is very limited, and it is difficult to break through

Therefore, its application is limited

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