Abstract: As the mining depth of mineral resources continues to increase，the stability of large-sec⁃ tion deep soft rock chambers has become one of the main technical challenges faced in mineral mining.Tra⁃ ditional support methods often exhibit significant deformation and failure when dealing with soft and frac ⁃ tured surrounding rocks under high stress and strong mining-induced influence，failing to ensure the long term stability of the chambers.The second-phase construction project of Zhongjiu Iron Mine is a typical project in complex strata.The complex strata have significant differences in rock properties，with devel⁃ oped faults and fractures，and the surrounding rock in the mining area is mainly composed of Class IV ba ⁃ sic rocks，with poor rock integrity and a hardness coefficient ranging from 2 to 9，belonging to a weak rock group.In response to major safety issues such as the difficulty in supporting and large deformation of the roof of the underground -550 m level central water pump room and similar large chambers in the mine，the upper extremely fractured roof of the water pump room was supported by "advanced pipe frame +steel truss +long anchor cables +deep and shallow hole grouting"，and the arch roof was constructed by grouting and full-length anchoring of the anchor cables.Field application shows that this combined support technology can effectively control the deformation of the surrounding rock of the chamber，significantly improve the bearing capacity and deformation resistance of the support structure，and provide a reliable solution for the support of deep soft rock chambers.The study conducted a detailed discussion on the key technical parame ⁃ters，construction techniques，and application effects of the combined support，with the aim of providing reference and inspiration for the design and construction of chamber support in similar conditions.

Key words: fractured soft rock, large chamber, combined support, grouting anchor cable, full-length anchorage