Damage control methods for detecting cement mixing piles by static cone penetration tests in reserved tubes

The problem of pile damage encountered when using cone penetration test (CPT) in a reserved tube for quality detection testing is addressed. Based on the experimental and numerical models, the damage control methods for CPT in reserved tubes are studied. The results of CPT show that the penetrating path of probe and the sensitivity of detection are influenced by the diameter and strength of the tube. The numerical results show that the damage degree of the pile depends on the diameter and thickness of the tube and strength of the pile, as opposed to the depth of cone penetration and strength of the tube. The equivalent plastic strain of the pile is negatively correlated to the diameter and thickness of the tube. The area of damaged zone is negatively correlated to the age of mixing pile and diameter of the tube. The maximum radius of the damaged area decreases with the increase of the tube diameter. In the field tests, the effective range of the sizes of tubes is determined in advance according to the numerical simulation, and the size of the tubes used in engineering tests are determined by the field tests, so as to achieve the goal of controlling the integrity of the damaged piles.