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以龙厦铁路象山特长隧道地质构造发育、埋深大于500 m段围岩压力及围岩变形的现场测试资料为依据,对大埋深隧道地质构造发育段围岩压力的特点、变形压力的形成机制等进行了研究。研究表明:大埋深隧道,结构面或褶曲、逆断层发育,但地下水不发育的地段,即使围岩强度较高,隧道开挖后仍可能出现较大的变形;围岩较大变形主要是由于在自重应力和残余构造应力作用下被挤密的结构面在隧道开挖后因侧向限制消除而张开、扩容引起的,受其影响,初期支护将受到较大的围岩变形压力。上述地段围岩压力具有下列特点:(1)地下水不发育区段的围岩压力比地下水发育区段的大;(2)隧道纵向发育向斜的区段,拱顶至拱腰段围岩压力最大,越趋向于向斜核部,拱顶围岩压力越大;(3)发育褶曲的断面,与褶曲轴线垂直方向的围岩压力较大;(4)发育逆断层的断面,与断层倾向相反侧的围岩压力较大,该侧断层面附近的围岩压力最大,对侧断层面附近的围岩压力最小;(5)下台阶的围岩压力比上台阶的小,两者的相对差随上、下台阶施工间隔时间的延长而增大。
Based on the field test data of surrounding rock pressure and surrounding rock deformation at the depth of 500 m and the geological structure of the Xiangshan super long tunnel of Longxia Railway, the characteristics of surrounding rock pressure and the formation of deformation pressure Mechanism, etc. were studied. The results show that large tunnel, structural surface or folds and reverse faults may develop but lots of groundwater are not developed. Even if the surrounding rock strength is high, large deformation may still occur after tunnel excavation. The large deformation of surrounding rock is mainly Due to the self-weight stress and residual tectonic stress, the compacted structural surface is expanded and expanded due to lateral restriction after tunnel excavation. Affected by this, the initial support will be subjected to large deformation pressure of surrounding rock . The surrounding rock pressure in the above-mentioned area has the following characteristics: (1) the surrounding rock pressure in the undeveloped groundwater zone is larger than that in the groundwater development zone; (2) (3) The section with developed folds has a large pressure to the surrounding rock perpendicular to the axis of fold; (4) The section with developed fault and the tendency of faults The pressure of the surrounding rock on the opposite side is larger, the surrounding rock pressure is the maximum near the side fault surface, and the pressure of surrounding rock near the opposite fault surface is the smallest. (5) The surrounding rock pressure of the lower step is smaller than that of the upper step, Difference with the upper and lower steps to increase the construction interval.