About the author:

1. CCCC First Highway Engineering Co., Ltd., Beijing 100024,China;2. School of Geosciences and Info⁃Physics, Central South University, Changsha, Hunan 410083,China;3. CCCC Chongqing Yuwu Expressway Co., Ltd., Chongqing 401520,China

Abstract:

Mountain areas are rich in mineral resources, and coal seams are fragmented. Constructingtunnels crossing coal measure strata, it is difficult to control the deformation of the surrounding rock.Construction disturbances can easily cause collapse of the tunnel arch and damage to the supportstructure. Based on a tunnel project, numerical simulation research on the mechanical characteristics oftunnel construction crossing coal measure strata was carried out. Different construction methods such asfull⁃face tunneling method, bench cut method, reserved core soil method were compared and analyzed fortheir stress and deformation characteristics in tunnel construction crossing coal measure strata. Theadaptability of different construction methods was discussed. The research results show that all threeconstruction methods will cause uneven settlement of the arch crown. The minimum settlement of the archcrown caused by the reserved core soil method is -9.06mm, and the minimum horizontal displacement is2.26mm. The maximum settlement and horizontal displacement of the arch crown caused by full⁃facetunneling method are - 15.28mm and 14.88mm respectively. Due to the good overall integrity of thelining, full⁃face tunneling method can effectively reduce the stress concentration on the arch crown andalleviate the degree of eccentric compression of the support structure. However, reserved core soil method and bench cut method have obvious stress concentration on the arch crown, causing tension on the leftside of the support structure and compression on the right side. From the overall construction analysis,full⁃face tunneling method rapidly increases the settlement of the arch crown in the early stage ofconstruction, and tends to stabilize after the lining is closed loop,while bench cut method has a largesettlement of the arch crown during the excavation of the upper platform,which is in a high⁃risk period.Although reserved core soil method involves more excavation steps, it can effectively control thedeformation of coal seam surrounding rock and has strong adaptability in tunnel construction crossing coalmeasure strata.