A karst geology rotary-dig cast-in-place pile hole-forming technology

Abstract

The invention discloses a karst geology rotary-dug cast-in-place pile hole-forming process, which comprises the following steps: (1) leveling the site; (2) laying out the pile foundation; (3) putting a rotary drilling rig in place; (4) laying a casing; (5) Preparation of mud stabilization fluid and replenishment of mud stabilization fluid in the casing; (6) Rotary drilling into holes (slow down the drilling speed when encountering karst caves or half rocks, and drill to the bottom when not encountering karst caves or half rocks design elevation); (7) primary hole cleaning and hole depth inspection; (8) installation of reinforcement cages and conduits; (9) gas lift reverse circulation secondary hole cleaning; (10) pouring underwater concrete (considering the existence of karst caves, Prepare 30 to 40 cubic meters of concrete more to prevent the cave from breaking down, and the concrete will drop sharply to cause waste piles); (11) Form piles and pull out the casing.

Description

technical field [0001] The invention relates to a pile foundation construction technology, in particular to a karst geological rotary-dug cast-in-place pile hole-forming technology. Background technique [0002] The construction technology of rotary drilling bored pile is a pile foundation construction technology that has emerged in recent years. At present, the existing construction technology of rotary drilling bored piles is: leveling the site → laying out the pile position → placing the rotary drilling rig in place → laying the casing → supplementing the stabilizing fluid in the casing → rotary digging to form a hole → clearing the hole and inspecting the hole Deep → install reinforcement cages and conduits → secondary hole cleaning → pouring underwater concrete → forming piles and pulling out the casing. The existing construction process quality control standards and construction process technical standards have no specific national construction method standards. The ...

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Problems solved by technology

The existing construction technology is aimed at the general geological conditions. If the general geological rotary drilling pile construction technology is copied in the karst area with complex geological conditions, different problems will arise. The most important problem is the deviation of the borehole. , Drill sticking, drill bit drop, incomplete hole cleaning, broken piles and waste piles, etc.

Due to the poor stability of the drilling rig installation, the unstable installation of the drilling rig or the bending of the drill pipe during operation, the soft ground or uneven hardness and other reasons, the drilling hole is deflected; , it will lead to problems such as drill sticking or bit drop; the rock fragments produced during the process of rotary drilling in karst areas are more than those in general geology, and the general hole cleaning method will cause incomplete hole cleaning, which will lead to There is a lot of sediment at the bottom of the pile, which seriously affects the quality of the pile foundation; due to the existence of karst caves, the karst caves may be broken down when pouring concrete, resulting in a sharp decline in the concrete, resulting in broken piles and waste piles

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