Rotary jet grouting expanding spiral soil-squeezing combined cast-in-place pile and pile forming method thereof

Abstract

The invention belongs to piles of building construction and pile forming technologies, and particularly relates to a rotary jet grouting expanding spiral soil-squeezing combined cast-in-place pile and a pile forming method of the combined cast-in-place pile. A hollow combined drilling tool with a concrete channel is adopted, wherein the outer side of an outer pipe of the drilling tool is provided with threads, or bumps or invisible bumps are spirally arrayed in the circumference on the outer side of the outer pipe. One or two rotary jet grouting pipes with the rotary jet grouting function are arranged between the drilling outer pipe and a core pipe or arranged on the outer side of the wall of the outer pipe, nozzles of the bottom end of the rotary jet grouting pipes are positioned on a drill bit, at least one nozzle is arranged on the outer wall of each rotary jet grouting pipe, and besides one nozzle can be arranged at the bottom of one rotary jet grouting pipe. The combined drilling tool is adopted for the rotary jet grouting expanding spiral soil-squeezing combined cast-in-place pile, while rotating soil-squeezing drilling is performed, rotary jet grouting is carried out, a larger expanded head can be partially formed at the pile end, and the rotary jet grouting goes on for secondary slurry replenishing when the drilling tool is lifted in a rotating mode, so that the diameter, strength, uniformity and the like of the rotary jet grouting pile meet design requirements. The bearing capacity of the combined pile formed by squeezing is improved substantially, the formed pile diameter is increased, and therefore while the bearing capacity of a single pile is improved, shearing strength and bending resistance are increased.

Description

technical field [0001] The invention belongs to building construction piles and a pile-forming process, in particular to a rotary-spray diameter-expanding spiral-squeezed soil combined cast-in-place pile and a pile-forming method thereof. Background technique [0002] 1. The patent CN96116902.5 announced by the Patent Office of the State Intellectual Property Office is named "Pile-forming Technology for Cast-in-place Threaded Pile". So far, there are few users because of the following shortcomings. The first step is to make a hole-forming machine Prefabricate the hole; the second step is to drill the long auger with full thread to the design depth. After the pile is formed, the core diameter is smaller than the design pile diameter. Because the cross-sectional area of ​​the pile is not enough, the pile body will be destroyed earlier than the bearing soil when it is under pressure. , the load-bearing and anti-pull force are small, and the reinforcement cage is difficult t...

AI Technical Summary

Problems solved by technology

[0002] 1. The patent CN96116902.5 announced by the Patent Office of the State Intellectual Property Office is named "Pile-forming Technology for Cast-in-place Threaded Pile". So far, there are few users because of the following shortcomings. The first step is to make a hole-forming machine Prefabricate the hole; the second step is to drill the long auger with full thread to the design depth. After the pile is formed, the core diameter is smaller than the design pile diameter. Because the cross-sectional area of ​​the pile is not enough, the pile body will be destroyed earlier than the bearing soil when it is under pressure. , the load-bearing and anti-pull force are small, and the reinforcement cage is difficult to place, the concrete protective layer is difficult to guarantee, and the thread is formed in the liquefiable soil layer and the weak soil layer, the soil around the pile is small, and the load-bearing and shear resistance of the pile are small. 2, the application date is July 8, 2003, and the name is "semi-screw pile and its pile-forming method" The deficiency that the patent exists is: when drilling into construction The required torque is large, because the drilling tool is not lubricated when drilling in the soil and forms a hard squeeze, so that the drilling often fails to reach the predetermined depth, and the drilling speed is slow; in addition, the soil itself is not a homogeneous body , so that the speed of drilling footage does not match the speed of rotation, it is difficult to form threads, and most of the formed threads are secondary wrapping after the soil rebounds. Therefore, the threads of the pile destroy the natural state of the soil. The bearing capacity of the soil is reduced. In addition, the upper 1 / 3L is linear, and the lower 2 / 3L is threaded. It is difficult to place the reinforcement cage, and it is difficult to ensure the concrete protection layer. In addition, it is difficult to ensure the concrete protection layer in the liquefied soil layer and the soil layer with low bearing capacity. 3. The application number is 200710063983.3, and the name is the patent of "Construction Method for Two-way Spiral Squeeze and Expand Pile and Two-way Spiral Closed Squeeze and Expand Drill Bit". There is no lubrication and the reverse thread on the upper part blocks the soil. For the soil with groundwater, the soil is squeezed very densely below the reverse screw part, and the water is almost squeezed out, so that the torque of the equipment is very large. After drilling to a certain depth The tremor is very serious, and the predetermined depth is often not drilled; 4. The application number is 200510014323.7, and the name is "construction method of synchronous composite pile with high-pressure rotary grouting pile tip". Cement-soil piles, and then use static pressure or vibration methods to sink the prefabricated piles to a predetermined depth, and at the same time squeeze the cement-soil piles to the surroundings, the diameter of the piles formed by the outer package is small, the uniformity is not ideal, and the bearing capacity is improved. Small; 5. Application No. 02132652.5, titled "Drilling High-pressure Jet Reaming Pressure Grouting Concrete Special-shaped Pile Forming Method and Device" is to use long auger soil drilling to reach the design depth. Spray high-pressure medium to expand the diameter of the hole, then press down the drilling tool to the bottom of the hole, and then rotate and lift the concrete to be poured. The disadvantage is that the bearing capacity of borrowing soil drilling is low, and there is soil pollution, so it can only be partially expanded. The drilling tool must be lowered for concrete pouring, the medium cannot be sprayed during the drilling process, the uniformity is very poor, and the increase in bearing capacity is small