The invention provides a roadbed widening door opening type
retaining wall structure and a construction method thereof. The
retaining wall structure comprises a bearing layer, a soft foundation is arranged on the bearing layer,
cement mixing piles are arranged in the soft foundation, an original roadbed is arranged on the soft foundation, the top of the original roadbed is an original
road surface, the side face of the original roadbed is a slope surface, a step-shaped platform is arranged on the slope surface, and two rows of
cement fly ash gravel piles are driven at corresponding positions to serve as foundation piles; the structure further comprises a door opening type
reinforced concrete frame, and the two bottoms of the door opening type
reinforced concrete frame are supported on the
cement fly ash gravel piles respectively; and light
foam concrete is filled between the left side of the door opening type
reinforced concrete frame and the step-shaped platform on the original embankment, and the top of the door opening type reinforced concrete frame is provided with a widened pavement which is in
butt joint with the original pavement. Differential settlement of the widened roadbed and the old roadbed can be effectively reduced, the stability of the roadbed is improved, the stability problem of the guardrail foundation is solved, on the premise that
land resources and the environment are protected, the cost of soft foundation treatment and
land acquisition is saved, the construction progress is accelerated, and good economic and technical benefits are achieved.