State of Advancement of Column-Type Reinforcement Element and Its Application in China

Abstract

Conventional column-type reinforcement elements have been widely used for ground improvement and they can be classified into three categories: (1) sand column and stone column; (2) deep mixed column, lime column, and jet grouted column; and (3) concrete solid piles, concrete pipe piles, and steel pipe piles. The column-type reinforcement elements of different categories exhibit different behavior and failure modes. Recently, new and composite column-type reinforcement elements have been developed, which combine two or three types of conventional column-type reinforcement elements into one column. The composite column is formed by installing a plain concrete, reinforced concrete, or steel pile of a small diameter in the center of the first or second type column to a desired depth. This composite column has much higher bearing and bending capacities than the conventional column-type reinforcement element in the first and second categories. The cost of the new type columns is competitive considering their higher capacities as compared with the conventional columns. This paper summarizes experimental studies and case histories on the behavior and performance of these composite columns used in China.