Abstract: In order to tackle the problem of large deformation at the crossover point of deep large section soft rock tunnel, this paper takes the crossover point of kilometer deep tunnel in Wanfu coal mine as an engineering example and applies microscopic negative Poisson’s ration (NPR) steel anchor cable in tunnel support for the first time. The deformation mechanism of the surrounding rock at the intersection of deeply buried roadways is analyzed, and a control countermeasure with microscopic NPR steel anchor cables as the core is put forward by using a combination of laboratory test, theoretical analysis, numerical simulation and field test. The mechanical properties of microscopic NPR steel anchor cables are studied by static tensile test in laboratory. The results show that the whole process of microscopic NPR steel anchor cables is characterized by high constant resistance, uniform tension, no yield platform, no obvious necking effect at break. Based on theoretical deduction and the maximum influence range of surrounding rock at T-type tunnel intersection, a calculation model of the maximum influence range of T-type tunnel intersection supported by microscopic NPR steel anchor cable is established. Through numerical simulation, the failure evolution process of T-shaped tunnel intersection is reproduced, and compared with the support effect of common microscopic NPR steel anchor cable. On-site support application test and monitoring are carried out. It verifies that the long-short microscopic NPR steel anchor cable combined support strategy has good control effect on large deformation of surrounding rocks at the intersection, which provides new support materials and means for safety and stability control of surrounding rocks at the intersection.

Key words: kilometer deep well, large section, T-type tunnel intersection, microscopic NPR steel anchor cable, roadway support