Field tests on detecting cement mixing piles by static cone penetration tests in reserved hole

The method of cement mixing pile (CMP) is often used to improve soft soil foundation. CMP quality detection is important to evaluate the effect of foundation improvement. As the specified method for the current code of China government, coring has the shortages of long cycle, high cost and low efficiency. The method of quick quality detection is studied though field and laboratory tests. The results show that the method of static cone penetration tests in the reserved hole can detect the quality of CMP continuously. The tip resistance in the 7th day has good linear relationship with the unconfined compressive strength in the 28th day. The linear parameters decrease with the increase of clay particles content. The tip resistance of static cone penetration combining with the unconfined compressive strength of core samples makes the standard curve and forms the rapid detection methods for CMP. The proposed method can shorten the time, accelerate the speed, reduce the cost and improve the reliability of the test results.