Half soil squeezing screw expansion pile forming method

Abstract

The invention belongs to a building construction method, and in particular relates to a half soil squeezing screw expansion pile forming method. The adopted combined drilling tool consists of a soil taking spiral drill bit (1) with at least two drill tips (1-1) and a soil squeezing threaded drill rod (2) connected with the spiral drill bit (1) or a polished rod (3) connected to the upper part of the spiral drill bit (1); the threaded drill rod has the characteristics that the diameter of the core rod is greater than that of a long spiral drilling tool, the blade is thick and the strength is higher; and according to the half soil squeezing screw expansion pile forming method, soil is taken by the drill bit part and squeezed by the threaded drill rod part, so that the torque is greatly reduced, the downward penetrating capacity is stronger, drilling is easy, pore forming or pile forming speed is increased, the soil squeezing effect is reduced, the penetrating capacity is enhanced, the torque is reduced, equipment faults are reduced, and the service life of the equipment is prolonged.

Description

technical field [0001] The invention belongs to a building construction method, in particular to a construction method of semi-extruded soil screw extruded and expanded into piles. Background technique [0002] At present, the commonly used pile-forming method in construction is long spiral concrete pile, which is a one-time pile-forming method with soil. This pile-forming method has the disadvantages of easy hole collapse, too much mud and sand drilled out, and low bearing capacity. , especially in the saturated fine sand layer, it is more difficult to form a pile, and the quality of the pile cannot be guaranteed; in addition, the blades of the long auger used are large and the speed is high. The earth and rocks at high places put the operators in danger. Compared with soil-squeezed piles and semi-soil-squeezed piles, the bearing capacity of soil-borrowing drilling is obviously lower, and the problem of empty soil at the pile end cannot be avoided during long spiral constru...

AI Technical Summary

Problems solved by technology

[0002] At present, the commonly used pile-forming method in construction is long spiral concrete pile, which is a one-time pile-forming method with soil. This pile-forming method has the disadvantages of easy hole collapse, too much mud and sand drilled out, and low bearing capacity. , especially in the saturated fine sand layer, it is more difficult to form a pile, and the quality of the pile cannot be guaranteed; in addition, the blades of the long auger used are large and the speed is high. The earth and rocks at high places put the operators in danger. Compared with soil-squeezed piles and semi-soil-squeezed piles, the bearing capacity of soil-borrowing drilling is obviously lower, and the problem of empty soil at the pile end cannot be avoided during long spiral construction. force will also decrease

The bearing capacity of the soil-squeezing pile is relatively high, but all the soil within the diameter of the pile must be squeezed out to the surroundings, so the torque is too large, and the penetration is limited due to the influence of the equipment capacity, and there are often designs that cannot be drilled. The required depth, low drilling tool speed, slow construction efficiency and too much difficulty in equipment requirements

[0003] The publication number published by the Chinese Patent Office is CN1152650, which is called the patent of "pile-forming technology for pouring threaded piles". This technology is rarely used at present because of the following disadvantages: 1. The pile-forming process is cumbersome, and the first step is to form holes. The prefabricated hole is mechanically made. The second step is to drill the long auger with full thread to the design depth of the pile. The diameter of the hole formed in the first step is smaller than the diameter of the designed pile hole, which is generally soil-extracting drilling; 2. Due to the small diameter of the threaded pile core behind the pile, it is difficult to place the steel cage, and there is a problem with the slenderness ratio of the pile. The threaded pile is formed in the liquefiable soil layer and the weak soil layer. 3. The drilling thread of the entire threaded pile is absolutely matched with the thread trajectory of the lifting drill, so it is more difficult to require construction machinery and equipment, so it is difficult to achieve real synchronous matching of the thread of the perfusion threaded pile; 4. If the diameter of the core rod is increased to solve the problem of high bearing capacity and insufficient concrete strength, the torque required is very large, which is difficult to achieve

[0004] The publication number published by the Chinese Patent Office is CN1482308, and the invention patent titled "semi-screw pile and its pile-forming method" is currently being promoted and used, but there are also the following disadvantages: 1. The construction speed is slow, because the process rotates into a pile The required torque is very large. In order to ensure the high torque, two decelerations are required during drilling to reduce the speed of the power head, so the speed is very slow; The power head is often twisted and cracked, which increases equipment investment and delays the construction period; 3. Because the torque is too large, it often happens that the predetermined design depth cannot be reached during drilling; 4. The threaded pile core of the half screw pile is smaller than the design pile diameter, it is difficult to meet the requirements of high bearing capacity. To meet the requirements of bearing capacity, it is necessary to increase the concrete strength and increase the amount of cement. In addition, the synchronous technology cannot be truly realized; the upper 1 / 3 length of the 5-half screw pile is linear , the lower 2 / 3 of the length is screw type, and the reinforcement cage can only be arranged in the straight section, which is strictly in accordance with the requirements of the current construction pile foundation technical specification for reinforcement, and this process cannot be implemented

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