장비개선에 따른 DCM 지반개량공법의

Abstract

The paper presents a case study addressing the design and construction aspects for DCM(Deep Cement Mixing) method employed as the foundation of a caisson type breakwater with heavy weight(10,700 ton/EA) and a high design wave height(H1/3=8.7m). The DCM was designed for Ulsan New Port North Breakwater Phase 1 project by optimizing the pattern of DCM columns with a combination of short and long columns and considering overlapped section between columns as a critical section against shear force. This paper presents the order of construction for a DCM method and characteristic of equipment such as the introduce of upper gateway, the improvement of mixing blades and rotating direction with axis of auger motors, the controlling of rotating velocity. Also, this paper introduces the standard of construction control decided from pilot test, and analyzes how many strength obtains compared design standard strength with a target strength in a design phaze

And, this paper analyzes the construction data and soil profile for South Breakwater Phase 2 Construction and Hwa-am Port Construction similar with that of North Breakwater Phase 1. From this data, this paper presents the increase effect of strength obtained from the improvement of construction equipment and design by analyzing unconfined compression strength and deformation modulus. The main results are summarized as follows: 1) The result of the field strength test for cored DCM specimens obtained that field strength overestimated to target strength as a result of the improvement of a mixing device, auger motor and the use of exclusive ship for a DCM method 2) The increase effect of strength such as a unconfined compression strength and deformation modulus for a DCM specimens concretely the increase of the mixing efficient due to the improvement of upper gateway, decrease of a space for mixing blades, and the increase of the improvemnet efficient on control of rotating number and velocity due to the increse of generationg power for a auger motors 3) Further, foundation method as a DCM method is reflected on the improvement item applied to this site, ensured safety, construction and economic feasibility through decrese of cement amount.