A method for drilling and pulling out prestressed anchor cables for foundation pit support

Abstract

The invention discloses a drilling and pulling-out method for a foundation pit supporting prestressed anchor cable, and relates to the field of treatment of the prestressed anchor cable of a foundation pit supporting system. The method comprises the following steps of A, construction preparation; B, dismounting of a prestressed anchor cable locking device; C, drilling by a drilling machine; D, first time of cavity filling; E, second time of cavity filling; and G, hole closing. The method has the beneficial effects that the method meets various construction requirements, the anchor cable is pulled out, the surrounding environment is not disturbed, and the pulling-out success rate of the prestressed anchor cable, namely safety of operators is ensured.

Description

Technical field [0001] The invention relates to the field of pre-stressed anchor cable treatment of a foundation pit support system. More specifically, the invention relates to a method for drilling, chiseling and pulling out a pre-stressed anchor cable for foundation pit support. Background technique [0002] Deep foundation pit support usually adopts the form of retaining pile + prestressed anchor cable. After the local lower chamber is backfilled, the prestressed anchor cable of the retaining structure loses its use function but intrudes into the underground space outside the original foundation pit. (Structure) Subsequent excavation and construction of structures will cause impacts. For example, when urban subway tunnels are constructed under the shield tunneling method, or when the surrounding new basement enclosure structure is constructed, the pre-stressed anchor cables in the early construction will cause huge obstacles to the construction. The construction difficulty and...

AI Technical Summary

Problems solved by technology

[0002] The support of deep foundation pits often adopts the form of enclosure piles + prestressed anchor cables. After the basement is backfilled, the prestressed anchor cables of the enclosure structure lose their function, but because they invade the underground space outside the original foundation pit, the surrounding buildings ( For example, when the urban subway tunnel adopts the shield method to pass through the construction, or the construction of the surrounding new basement enclosure structure, the prestressed anchor cables of the previous construction will cause huge obstacles to the construction, adding Increased construction difficulty and safety risks, increased construction economic costs and construction period costs

[0003] At present, in addition to the retrievable prestressed anchor cable, the main method for pulling out the intruded prestressed anchor cable is to release the locking of the tension end, and apply the prestress by using a through-hole jack until the anchoring force exceeds the anchor cable and the anchor cable fails. Pulling out, this method cannot control the critical point of the anchoring force failure of the anchor cable, there may be a situation where the anchor cable is broken and the anchor section cannot be pulled out, and the anchor section is loose or the ejection force generated by the instantaneous prestress of the anchor cable breaks There are great potential safety hazards for the operators, and the reliability rate is low and unsafe; the second is to use manual excavation of the shaft to cut off the anchor cables in sections and pull them out. This method needs to occupy a certain amount of work space on the ground outside the enclosure structure , it is not suitable for use in areas with heavy traffic or areas with structures, and there is uncertainty in the control of the intersection between the vertical excavation direction and the anchor cable construction direction, resulting in high safety risks, long construction period, and high cost; the third is to use shield tunneling The open-cup cable-cutting method requires modification of the shield machine’s cutter head and cutters, and takes a long time to process, posing a greater safety hazard

[0004] Ordinary prestressed anchor cable removal methods cannot meet today's construction requirements. How to pull out the failed abandoned prestressed anchor cables when the basement has not been backfilled and there is still work space, without causing disturbance to the surrounding environment and ensuring the prestressed anchor cables. The success rate of pulling out the cable and the safety of the operators have become the primary problems to be solved by this method.

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