The prefabricated and assembled integrated pipe gallery has high construction efficiency and easy quality control, which can effectively shorten the on-site construction period and reduce the comprehensive construction cost. In view of the four types of typical prefabricated integrated pipe gallery structure systems in the current project (ie, the whole cabin prefabricated integrated integrated pipe gallery, the laminated plate assembled integrated pipe gallery, the prefabricated plate assembled integrated pipe gallery and the prefabricated trough type assembled integrated pipe gallery), more It systematically introduces its structural characteristics and scope of application. On this basis, the structural design method and engineering application of my country's prefabricated integrated pipe gallery are sorted out, and the research and application of the prefabricated integrated pipe gallery structure in my country are prospected in the future.

01 Structural system

Aiming at the four common prefabricated and assembled integrated pipe gallery structural systems, it focuses on its structural characteristics and scope of application.

The whole cabin prefabricated and assembled integrated pipe gallery

The main feature of the whole cabin prefabricated and assembled integrated pipeline gallery is the overall prefabrication in the cross-sectional direction, and the longitudinal direction is divided into sections of a certain length (usually about 2m) as required. The longitudinal connection of the precast sections of the whole cabin prefabricated and assembled integrated pipe gallery generally adopts prestressed tendons or bolted connections. Restricted by transportation and hoisting conditions, the whole-cabin prefabricated integrated pipe gallery is generally suitable for single-cabin or double-cabin integrated pipe gallery with small cross-sectional dimensions. The structure of a typical whole cabin prefabricated and assembled integrated pipe gallery is shown in Figure 1.

Figure 1 The whole cabin prefabricated and assembled integrated pipe gallery

Fig． 1 Integrated precast assembly utility tunnel

Laminated board type assembled comprehensive pipe gallery

The main feature of the laminated composite pipe gallery is to divide the side wall, top plate and bottom plate into blocks. The side wall adopts double-sided laminated structure. The top plate generally adopts the laminated floor structure, and the bottom plate generally adopts the integral cast-in-place or laminated structure. , A typical superimposed panel assembled integrated pipe gallery is shown in Figure 2. At the construction site, each prefabricated block is connected by a post-cast laminated layer. The superimposed slab-assembled integrated pipe gallery is generally also connected by post-cast laminated layers in the longitudinal direction. The longitudinal length of each prefabricated block is determined according to the transportation and lifting conditions (generally 4-6m). Since the prefabricated sub-blocks such as the bottom plate, side walls and top plate can be freely combined, the superimposed panel assembly integrated pipe gallery has a wide range of applications and is currently the largest prefabricated integrated pipe gallery structure system in China.

Figure 2 Laminated board type assembled comprehensive pipe gallery

Fig． 2 Precast assembly utility tunnel composed of composite slabs

Prefabricated panel assembled integrated pipe gallery

The structural characteristics of the prefabricated panel assembled integrated pipe gallery are similar to those of the laminated panel assembled integrated tube gallery. The difference between the two is that the side walls, top and bottom plates of the prefabricated panel assembled integrated tube gallery generally adopt prefabricated solid panel structures. In the construction site, the side wall and the bottom plate can be connected by sleeve grouting or bolts, and the side wall and the top plate are generally connected by post-cast node core area or post-cast laminated layer, as shown in Figure 3. The prefabricated slab assembled integrated pipe gallery is generally connected by post-cast sections in the longitudinal direction, and the longitudinal length of each prefabricated block is determined according to the transportation and hoisting conditions (usually about 4m). The combination and assembly of each prefabricated block of the structural system is more flexible and has a wide range of applications.

Figure 3 Prefabricated panel assembled integrated pipe gallery

Fig． 3 Precast assembly utility tunnel composed of precast solid slabs

Prefabricated trough type assembled comprehensive pipe gallery

The main feature of the prefabricated trough-type assembled integrated pipe gallery is that it is divided into two single-trough or multi-trough prefabricated blocks in the cross-sectional direction, and the pre-stressed tendons, bolts, sleeve grouting, etc. are used at the construction site Make a connection. The prefabricated trough-type assembled comprehensive pipe gallery is generally connected by prestressed tendons or bolts in the longitudinal direction. Due to transportation and hoisting conditions, the longitudinal length of each prefabricated section of the prefabricated trough-assembled integrated pipe gallery is generally 2 to 3m, which is mainly suitable for integrated pipe gallery with ≤ 4 cabins. A typical 3-cabin prefabricated trough type assembled integrated pipe gallery is shown in Figure 4.

Figure 4 Prefabricated trough type assembled comprehensive pipe gallery

Fig． 4 Precast assembly composed of precast groove-shape elements

02 Structural design method

The structural design method of the prefabricated integrated pipe gallery has an important influence on its large-scale promotion and application. At present, my country has not promulgated technical standards specifically for the structural design of prefabricated and assembled integrated pipe corridors. The GB50838-2015 "Technical Specification for Urban Comprehensive Pipe Gallery Engineering" only preliminarily stipulates the structural design of the whole-cabin prefabricated integrated pipe gallery and the single-cabin prefabricated trough-assembled integrated pipe gallery. The main contents are as follows.

1. The cross-sectional internal force calculation model of the whole cabin prefabricated integrated pipe gallery structure with only longitudinal joints should adopt the same closed frame model as the cast-in-place concrete integrated pipe gallery structure.

2. The cross-section internal force calculation model of the single-cabin prefabricated trough-type assembled integrated pipe gallery with longitudinal and transverse joints should consider the influence of joints.

3. The structure of the prefabricated and assembled integrated pipe gallery should adopt prestressed rib connection joints, bolt connection joints or socket joints.

4. The waterproofing of the joints of the prefabricated integrated pipe gallery shall adopt the prefabricated elastic gasket as the main waterproof measure, and the interface stress of the elastic gasket shall be ≥1.5MPa.

The above regulations provide a certain technical basis for the promotion and application of prefabricated integrated pipe gallery, but the content is relatively simple, and key design parameters such as joint bending stiffness and joint shear resistance need to be further clarified. In addition, the scope of application of the above-mentioned regulations is limited, and it does not include the superimposed slab assembled integrated pipe gallery, prefabricated slab assembled integrated pipe gallery and multi-cabin prefabricated trough assembled integrated pipe gallery commonly used in current projects.

At present, the "Specifications for Prefabricated and Assembled Comprehensive Pipe Gallery Structure Design", led by Tongji University and Shanghai Municipal Engineering Design and Research Institute (Group) Co., Ltd., participated by China Railway Fourth Bureau Group Co., Ltd. and China State Construction Co., Ltd. is under intense preparation . The promulgation and implementation of this standard will provide support for the large-scale promotion and application of prefabricated integrated pipe gallery structures.

03 Typical engineering application

The comprehensive pipe gallery demonstration section of the Shanghai World Expo Park (completed in 2007, 200m long) is the first comprehensive pipe gallery in my country with a prefabricated assembly structure system. Since then, with the continuous development of the prefabricated integrated pipe gallery structure system and the large-scale construction of integrated pipe gallery projects, the prefabricated integrated pipe gallery has also developed rapidly in my country. Several types of typical prefabricated integrated pipe gallery projects are introduced as follows.

The whole cabin prefabricated and assembled integrated pipe gallery

The prefabricated sections of the whole-cabin prefabricated and assembled integrated pipe gallery have a large self-weight and are subject to transportation and lifting restrictions, and are mainly suitable for single-cabin and double-cabin integrated pipe gallery. Typical projects include the comprehensive pipe gallery project in the Shanghai World Expo Park and the comprehensive pipe gallery project in Shiyan, Hubei. The single-cabin whole-cabin prefabricated integrated pipe gallery of the Shanghai World Expo Park is shown in Figure 5, and the double-cabin whole-cabin prefabricated integrated pipe gallery of Shiyan, Hubei is shown in Figure 6.

Figure 5 The whole cabin prefabricated and assembled integrated pipe gallery (single cabin) in the Shanghai World Expo Park

　　Fig． 5 Integrated precast concrete utility tunnelin Shanghai Expo area ( single compartment)

Figure 6 Hubei Shiyan whole cabin prefabricated and assembled integrated pipe gallery (double cabin)

　　Fig． 6 Integrated precast concrete utility tunnel in Shiyan ( double compartments)

Laminated board type assembled comprehensive pipe gallery

The superimposed panel assembled integrated pipe gallery is currently the most widely used prefabricated integrated pipe gallery in my country. A typical project is a double-cabin superimposed slab assembly integrated pipe gallery on the first longitudinal road of Haikou Meian. As shown in Figure 7.

Figure 7 Haikou superimposed slab assembly integrated pipe gallery (double cabin)

Fig． 7 Precast concrete utility tunnel composed of composite slabs in Haikou ( double compartments)

Prefabricated panel assembled integrated pipe gallery

The prefabricated panel assembled integrated pipe gallery greatly reduces the amount of on-site wet work on the basis of the laminated panel assembled integrated pipe gallery. But the waterproof performance and safety of its connecting seams need to be paid attention to. At present, there are few prefabricated slab assembly comprehensive pipe corridors actually used in the project. Zhongshan, Guangdong has carried out the construction of a trial section, as shown in Figure 8.

Figure 8 Guangdong Zhongshan prefabricated panel assembled integrated pipe gallery (double cabin)

Fig． 8 Precast concrete utility tunnel composed of precast solid slabs in Zhongshan ( double compartments)

Prefabricated trough type assembled comprehensive pipe gallery

Compared with the prefabricated integrated pipe gallery of the whole cabin, the prefabricated trough-type assembled integrated pipe gallery can greatly reduce the weight of the prefabricated components, and at the same time significantly reduce the on-site wet work and assembly workload, which has a good application prospect. Typical projects are the comprehensive pipe gallery project in Liupanshui City, Guizhou. As shown in Figure 9.

Figure 9 Guizhou Liupanshui prefabricated trough type assembled comprehensive pipe gallery (double cabin)

Fig． 9 Precast concrete utility tunnel composed of groove-shape elements in Liupanshui ( double compartments)

04 Conclusion

Generally speaking, the research and application of prefabricated integrated pipe gallery in my country started relatively late, but under the guidance of national policies and the active participation of relevant units, phased results have been achieved. From the perspective of further technological innovation and promotion and application, the following work remains to be carried out.

1. Aiming at the large cross-section and multi-compartment integrated pipe gallery, develop a new type of prefabricated integrated pipe gallery structure system with simple connection structure, fast construction speed and reliable quality.

2. For different prefabricated and assembled integrated pipe gallery structural systems, a calculation model for the bearing capacity and deformation of the integrated pipe gallery considering the influence of joints is established, and the system design method is proposed.

3. Considering the joint work of soil and structure, carry out research on seismic performance of prefabricated and assembled comprehensive pipe gallery.

4. Further carry out research on waterproof measures for the joints of the prefabricated integrated pipe gallery to improve the comprehensive waterproof performance of the prefabricated integrated pipe gallery.