## 1 Introduction
Aiming at the characteristics of engineered curve shape, multiple segments, and road complexity, [PERSON] et al. [9] adopted the multi-point unidirectional double-launching method. Through real-time monitoring, issues like detachment between the steel girder and the incremental launching platform during the incremental advancement were resolved. [PERSON] et al. [10] examined the comprehensive and specific mechanical behaviors of a wide-spancable-stayed bridge with dual towers and dual cable planes during incremental launching construction. [PERSON] et al. [11] designed the incremental launching construction scheme of suspension stiffening chords through a comprehensive analysis of Jinan Huanghe rail-cum-road Bridge, and effectively implemented it in the construction of huge steel truss girders. [PERSON] et al. [12] monitored the spatial configuration and internal loading of the steel box girder in the whole process of incremental launching, modified the relevant parameters based on the on-site construction conditions and initial stress condition of steel box girder, and compared the modified theoretical value and monitoring value. [PERSON] et al. [13] investigated the impact of local stress and deviation error in steel box girders while performing skew incremental launching under two working conditions. In terms of finite element analysis, [PERSON] et al. [14] utilized the ABAQUS software to model the incremental launching process of steel box girders, aiming to better understand and reduce the complex stresses generated during the process, and analyzed the mechanical properties and local buckling of steel box girders. [PERSON] et al. [15] studied the structural characteristics of steel U-shaped girders during incremental launching and proposed local stress control measures based on finite element analysis. [PERSON] et al. [16] studied the feasibility of using incremental launching for the construction and assembly of continuous hybrid arch-girder bridges by combining experimental and numerical methods. [PERSON] et al. [17] conducted finite element numerical modeling of the incremental launching process of a steel bridge and verified it by a laboratory scale-reduced test. [PERSON] et al. [18] utilized the finite element method to investigate the feasibility of incremental launching construction for a 180 m main span long-span bridge without auxiliary supports. [PERSON] et al. [19] advanced a construction approach for the bidirectional incremental launching and mid-span closure of long cantilever steel box girders. On this basis, a finite element model for pre-camber calculation was established. The study results demonstrate that the mid-span closure method substantially boosts construction efficiency. [PERSON] et al. [20] created a finite element model for the incremental launching of steel box girders, evaluated the local stress under the maximum cantilever condition and the stress distribution during vertical jacking asynchrony and lateral deflection, and formulated a dual-parameter control formula for incremental launching. Presently, few studies have been conducted on the control and monitoring technology of incremental launching construction for small-curvature-radius longitudinally variable-slope steel box girder bridges. Based on this, this paper studies the incremental launching process and full-process monitoring of a steel box girder bridge with a two-way slope, small curvature radius, large lateral deviation of the front end of the main girder, and difficulty in correcting the deviation, so as to guide the incremental launching design and construction of other ramp bridges in the project and offer guidance for the incremental launching construction of other small-curvature steel box girders.