Buried Tunnel Surrounding Rock Stress Release Law Research

In the Gui-Guang high-speed rail Northridge Cairn Tunnel engineeringbackground, the research tunnel section for the weak surrounding rock, in whichthe lot depth, high ground stress, poor hydrogeological harsh constructionenvironment under various adverse effects, analysis of tunnel The rock stressrelease timing of laws and best support.Collected at the project site excavation and support the convergence of threedifferent Northridge mountain tunnel surrounding rock geological conditions of thesurrounding rock sinking vault, tunnel support structure axial force of bolt axialforce and the measured the data. The three sections of a typical the Northridgemountain tunnel surrounding rock geology, the first paragraph of the surroundingrock fault after the surrounding rock crushing, the higher grade; second paragraphof the surrounding rock depth of the tunnel, high ground stress of surrounding rocksoft surrounding rock surrounding rock grade higher, with a large deformation;third paragraph of the surrounding rock is fractured surrounding rock, thesurrounding rock grade for the entire tunnel, and the strong water-rich area; Longmonitoring of these three cross-section measurement, data processing and summaryof the law of tunnel surrounding rock stress release and the surrounding rockdeformation in three different surrounding rock geological conditions in the tunnel,the first paragraph of the surrounding rock of tunnel surrounding rock stabilityminimal impact on the surrounding rock deformation and force is the smallest; thesecond paragraph of the surrounding rock with a large deformation, deformationrate is slow, but a longer duration, have a certain impact on the tunnel stability andsupport, support the timing of the surrounding rock stability is the key issue to besolved; the highest level of the third paragraph of surrounding rock, the mostbroken, the strong water-rich groundwater conditions adversely affect the stabilityof surrounding rock, the largest of the segments surrounding rock deformation, thebolt axial force, should focus on the early support.Use of underground engineering the tunnel finite element analysis software ofMIDAS/GTS numerical simulation software, simulation of the measured threesection tunnel construction operations, the surrounding rock of tunnel convergenceand crown settlement bolt axial force, the supporting structure axis force and rule,the results of field monitoring measurements.Finally, the tunnel-soft surrounding rock, best supporting timing were discussed, from space, the physical significance of the timing of the best supportand the radius of plastic zone correction, Fenner formula to determine the typicalcategories of rock ’s best support time.