Variable diameter drill pipe apparatus, variable diameter mixing pile and method of construction thereof

By using a variable diameter drill rod device and a tapered pile design, the problem of limited bearing capacity in traditional cement mixing piles has been solved, and the bearing performance of the pile has been significantly improved, especially in soft soil foundations.

CN122446997APending Publication Date: 2026-07-24CHINA RAILWAY 19TH BUREAU GRP EAST CHINA ENG CO LTD
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Patent Information

Application Number
CN202610549322.4
Authority / Receiving Office
CN · China
Patent Type
Applications(China)
Current Assignee / Owner
Filing Date
2026-04-23
Publication Date
2026-07-24

AI Technical Summary

Technical Problem

In traditional cement mixing pile technology, the equal diameter piles fail to fully utilize the differences in bearing capacity of soil layers at different depths, resulting in limited improvement in pile bearing capacity. This is especially true in deep soft soil foundations where the pile end resistance is low and the side friction resistance is limited.

Method used

A variable diameter drill rod device is used, in which the spiral blades on the outer periphery of the drill rod gradually increase in size from one end of the adjacent drill bit to the other, forming a conical pile. Combined with pressure sensors to monitor the grouting pressure and water-cement ratio, the cement grout and soil are fully mixed and solidified, forming a conical mixing pile.

Benefits of technology

It significantly improves the bearing capacity of the pile body. By increasing the diameter, it utilizes the side friction of the shallow soil and reduces the disturbance to the deep soft soil, thereby increasing the overall bearing capacity by 30-50%.

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Abstract

The present application relates to the technical field of foundation reinforcement, and especially relates to a variable-diameter drill rod device, a variable-diameter mixing pile and a construction method thereof, the variable-diameter drill rod device comprises a drill rod body, a grouting port is arranged on the outer periphery of the drill rod body, the grouting port is in communication with a grouting channel in the drill rod body, a spiral blade is arranged on the outer periphery of the drill rod body and extends along the axial direction of the drill rod body, and a drill bit is arranged at the end of the drill rod body, wherein the diameter of the spiral blade gradually increases from one end adjacent to the drill bit to the other end, the tapered pile body formed by the variable-diameter drill rod device fully utilizes the bearing capacity of the shallow soil body through the increased diameter of the upper part, the lateral extrusion effect is generated on the lateral slope of the pile under the action of the load, and the bearing capacity is significantly improved compared with the equal-diameter pile body.
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