Research On The Application Of Flexible Concrete Formwork In Underground Engineering

Because of the deficiencies in the field of underground engineering supporting methods, Xi'an University of Science and Technology (XUST) proposed a new supporting technology named Flexible Formwork and Pumped Concrete Supporting Technology(FFPCST). Based on FFPCST, this thesis mainly studies the application research of flexible concrete formwork in underground engineering.Generally, steel formwork and wooden formwork work widely in underground engineering, which are installed by steel trolley. FFPCST introduces fiber flexible formwork into underground engineering first time. The flexible formwork in this technology is made of double-layer fiber cloth sewing into a pocket in the shape of cuboid, which is fixed to surround the roadway inside by bolt and rebar net and then filled with pumped concrete during construction.The flexible formwork in FFPCST is required to have the characteristics of permeating through water and not concrete slurry to filter out superfluous water of injected concrete in flexible formwork. In order to meet the design requirement of the technology,high strength filament woven fiber cloth is chosen to sew flexible formwork as raw material, which mainly plays the role of filter in FFPCST.We should test the performances of fiber cloth to ensure that the flexible formwork can work well for FFPCST, including physical properties, mechanical properties in civil engineering and hydraulic engineering , durability and performance of the special requirement for coal mine and so on, so that the fiber cloth sewing flexible formwork can meet the design requirements.The design principle of flexible formwork consists of three aspects: fiber flexible formwork, bolt suspension formwork technology and compound concrete pre-stressed by fiber and rebar. Since flexible formwork is a key component of FFPCST, its thickness, length and width all have specific design requirements; meanwhile preserved bolt-hole and pump concrete nozzle need be set aside. Flexible formwork fixed inside roadway, its length is much longer than its width, so vertical reinforced strand is stronger than horizontal reinforced strand in fiber cloth, and there is a rope in the interchange of two reinforced strands to control the thickness of flexible formwork.Based on Jinfeng coal mine, this thesis designs a suitable flexible formwork to cross-section of the vice-inclined shaft, and describes its construction technology. Thus, we can find the flexible formwork's value of works.Choosing a proper material of flexible formwork, testing the corresponding material's performance, according to the system parameter design method, basing on examples of successful project, it shows that the flexible concrete formwork's application research is scientific, so that FFPCST can be popularized and used wide.