## 1 Introduction  
Nowadays, traditional primary support, mainly made of sprayed concrete and steel frame, has been widely used in underground engineering such as foundation pits and tunnels. It is applied through a process by which concrete or mortar is sprayed onto a surface to produce a compacted, self-supporting, and load-bearing layer [1]. Although traditional support is highly mature, it still has lots of drawbacks as well. Firstly, concrete is a kind of brittle material and can hardly bear any tensile stress. Secondly, problems such as large dust, high rebound rate, and poor quality stability are common during the construction of sprayed concrete [2]. In particular, a high rebound rate will not only cause quality defects due to the too-thin thickness of sprayed concrete but also waste material resources and increase construction costs. In order to solve the above problems, some scholars have proposed a steel corrugated plate as the main body of the support structure [3, 4]. Firstly, as a kind of construction material, steel is very popular in civil engineering, and has been studied in great depth for its composition and properties [3, 5]. Secondly, the mechanical analysis of steel-concrete composite structures is a hot topic in civil engineering research as well [6, 7, 8]. Corrugated steel structures are favored by engineers because of their advantages, such as high strength, easy maintenance, convenience of the construction process, and environmentally friendliness. For example, the mechanical properties of corrugated steel plate shear walls under cyclic loading were investigated [9]. Besides, the performance of corrugated steel supports under seismic loads was also studied [10, 11]. Then, in view of the characteristic that steel is liable to get rusty, related research on anticorrosive corrugated steel has been carried out [12; 13; 14]. However, how to ensure that the steel corrugated plate structure maintains close contact with the excavation surface and reduces voids is the main challenge affecting its popularization and application in underground engineering. In response, this paper proposes using mold bag concrete to fill the void between the corrugated steel plate and the excavation face. In recent years, geosynthetics such as geotextiles have gradually been used in various fields of civil engineering, such as structural seismic, material reinforcement, and new building materials [15; 16; 17; 18]. Among them, a mold bag is one of the geosynthetics, which is a double-layer bag-like fabric woven by a machine from high-strength chemical fiber filaments with engineering characteristics of permeability, air permeability, and impermeability to slurry [19]. Therefore, the mold bag concrete relies on this characteristic of the mold bag, relying on self-weight and the pressure of the grout pump to discharge excess water from the pores of the mold bag, which reduces the water-cement ratio and achieves the design strength after solidification [20; 21]. In China, mold bag concrete is widely used in canal and slope protection engineering because of its unique advantages. As fabric can only be loaded with tensile stress, fabric pretension is essential, and [PERSON] and [PERSON] [22] constructed two prototype shell structures based on numerical modeling to control the prestress applied to the fabric. [PERSON] and [PERSON] [23] proposed a new numerical method for determining the shape of flexible, impermeable, and inextensible suspended fabric sections affected by hydrostatic loads imposed by wet concrete. Moreover, [PERSON] and [PERSON] [20] obtained the relationship between the compressive strength of molded concrete and the mechanical parameters of the formwork and concrete based on destructive tests on concrete specimens molded in different fabrics. In summary, there are two main advantages to using fabric formwork in general. Firstly, it saves energy and reduces greenhouse gas emissions, making for more sustainable designs.