Cable construction is often used in slope and chamber surrounding rock reinforcement engineering, but it is not used in vertical construction of non-weathering hard gabbro rock under pile foundation. For the non-weathering hard gabbro rock layer under the pile hole, because of the stable and hard geological structure, the punching pile foundation can not meet the design depth. The existing construction methods often bring about some problems that need to be overcome, such as ultra-deep hole (16m and 26m), easy deviation hole, large verticality deviation, serious ash cleaning pollution, incomplete hole cleaning, poor elasticity of grouting pipe too long, easy deformation of anchoring cable and difficulty of grouting pipe withdrawal.
Technical implementation elements:
The technical problem to be solved by the invention is to provide a construction method of anchor cable for non-weathered hard rock pile foundation, which can improve construction efficiency, shorten construction period and reduce construction cost.
The technical scheme adopted by the invention to solve the technical problem is: the construction method of anchor cable on pile foundation of non-weathered hard rock comprises the following steps:
(1) Determination of anchor hole drilling time: anchor hole drilling time is the 7th day of pile concrete maintenance;
(2) Site arrangement and setting up the working platform: make technical preparation, labor organization preparation, material preparation, industrial tools and site preparation, and set up the rig working platform;
(3) Foundation retest: the total station is used to measure and position the construction site, and the axis survey, pay-off and elevation survey are carried out;
(4) Installation of drilling rig: the mechanical equipment, measuring instruments and testing instruments required for construction will enter the field, among which the footing shall be fixed on the ground using triangular support; The verticality of the hole should be monitored every 500mm after the process, and should be corrected in time when the deviation is greater than 2mm;
(5) Forming holes:
a. The actual drill diameter is greater than or equal to the design aperture, and the actual drilling depth is greater than the design depth of 0.5 to 1m;
b. Control of the verticality of the anchor hole: the deviation of the central position of the drilling hole and the positioning of the anchor hole should be ≤20mm at the pile center; The footing shall be fixed on the ground by triangular support; The verticality of the drilling process shall be monitored after every 500mm process, and the deviation shall be corrected in time if it is greater than 2mm.
c Ash removal
Look, the anchor cable drilling time standard is 24 hours
Anchor cable holes should be selected according to the formation of the corresponding anchor cable drill, it is strictly prohibited to boil water drilling and washing hole wall. In the process of drilling, construction records should be carefully made, such as formation conditions, groundwater conditions, etc. The hole diameter and hole depth shall not be less than the design value, and the over-drilling shall not be less than 40cm. After drilling to the design depth, the drilling shall not be stopped immediately, and the stable drilling shall be required for 3 to 5 minutes, and the anchor hole shall be cleaned in time. Anchor cable installation can be carried out only after anchor hole drilling is completed. After the completion of the anchor hole drilling, the anchor bar should be installed and the anchor hole grouting should be carried out in time. In principle, it should not exceed 24 hours to avoid the hole collapse caused by long-term shelving.
24 hours.
The main requirements of the anchor hole are to ensure the hole depth, aperture and Angle of the hole. Ensure the hole diameter; The downward inclination deviation is not more than 1°; Over-drill 50cm to avoid sludge affecting the effective hole depth. After the depth is reached, the mud is used to clean the hole wall and bring out the sediment. Anchor rod (anchor cable) frame beam construction, after each drilling holes should be installed in a timely manner, the interval shall not exceed 24 hours.