Research On The Support Technology For High Stressed Soft Rock Roadway With Composite Fail Ure

Supporting in soft roadways is always a puzzle for underground roadway engineering, especially for deep mining, where the surrounding rock of roadway often emergence some composite failure features, including high stress bulk increase, creep, and water-absorbent swelling in a complex geological environment coupled with high stress. Accordingly, the surrounding rock of roadway appears some complex fracture modes, such as large area reduction, rib spalling and floor heave and so on. In these cases rock roadway takes place prominen, surrounding rock seriously cracked, and the stability control of the surrounding rock becomes quite difficulty, which will result in a serious threaten to high efficiency and safe mining. In view of this, the support problems of deep soft rock roadway had been invesigated in order to find a right way of supporting. In the present, some complex environment conditions had been considerd, such as in-situ high stress, peculiar rock properties and stratification.The destruction causes and falure mode of soft rock in deep roadway were analyzed via a theat amount of field survey and deformation measurement, the cause as well as mechanism of floor heave were discussed. The obtained results revealed that deep soft rock roadway influenced by many factors is of serious strata behaviors and the deformation of confirning rock in deep soft rock roadway shows a strong age-characteristic.To deal with the problems caused by large deformation and confined aquifer during the course of in-situ stress measurement, some effective technical renovation were applied using a LUT 3D in-situ stress testing system imported from Sweden, the in-situ stress distribution in this mining area was revealed using this system, which can offer a real and exact boundary condition for supporting design.Using an advanced testing system and self-made dilatometer, we preformed a great amount of researches on mineral component, micro-structure, strength as well as deformation characteristics, hydrolytic weakening properties and creep property of confining rocks. These researches will be helpful to reveal the cause and mechanism of composite failure of red shale from the aspect of lithology.By means of discrete element method, and considering the real characteristics of fracture surface and the observed mechanical parameters, the deformation tendency and laws of soft rock in deep roadway under high in-situ stress condition were revealed.Using numerical simulation analysis, experimental and field tests, behaviors of ground pressure and deformation activities of high stress soft rock roadway, temporal-spatial evolution and instability mechanism of broken rock zone were revealed under the participation of multi-variable coupling. A specially designed deformation-coordinated bolt fitting for highly stressed and largely deformed rock mass was developed, which can provide not only a large deformation capacity, but also a strong supporting force. These new bolts have been successfully used in supporting construction of soft rock roadway in deep mining. Meanwhile, based on the deformation rules of soft rock observed in deep roadway, some new support techniques suitable for this type of roadway are proposed using the transformation technology, which can make composite failure mode turn into single failure. Through large-scale industrial field tests and long-term dynamic monitoring for roadway stability, the support design was tested and optimized, which provided an economical and reliable support method for safe and efficient deep mining.