为解决活动断裂影响区隧道建设过程中支护变形、开裂、破坏等问题，依托华丽高速东马场1号隧道进行研究。该隧道穿越程海—宾川活动断裂，施工过程中初期支护表现出变形量大、初期变形速率大且不易收敛、变形持续时间长、变形破坏不均匀等特点。受程海大断裂影响，隧址区地质构造应力水平高且以水平构造应力为主，断裂影响范围超过2 km。通过监测数据与试验结果分析，结合已开挖段隧道支护变形、开裂、破坏等情况，提出“长短结合、主动控制、分层支护、及时成环、预留内空”的综合支护体系。现场监测数据分析发现： 1）优化方案实施后，累计沉降平均值增加了12.46%，累计收敛平均值增加了26.57%，这是由于工序增加、工序消耗时间长引起的。2）实施优化方案后围岩变形主要集中在第1层初期支护阶段，该部位本身开挖产生的变形值占总变形值的70%，其余部位开挖产生的变形值占总变形值的30%；第2层初期支护及仰拱施作后，变形速率明显降低，二次衬砌浇筑前变形速率可控制在0.8~1 mm/d。
A case study is conducted on the Dongmachang No. 1
tunnel of the Huali expressway crossing the ChenghaiBinchuan
active fault to address the issues of support deformation, cracking, and
destruction during tunnel construction in areas with active fractures. A high
amount and rate of uneven destruction with a long duration and difficulty in
achieving convergence are observed for the deformation of the primary support
of the tunnel during the construction. Because of the influence of the Chenghai
fault, the geological tectonic stress level(considering the horizontal tectonic
stress as the main stress) in the tunnel site is high, and the section affected
by the fault exceeds 2 km in length. Using the analytical results of the monitored
data and test results, a comprehensive support system using a combination of
long and short supports, active control, layered supports, timely ring close,
and reserved inner space is proposed based on the deformation, cracks, and
destruction conditions of the tunnel support in the excavated section. The
analytical results of the monitoring data show the following: (1) The average
cumulative settlement and average cumulative convergence after implementing the
optimized plan are, respectively, 12.46% and 26.57% higher than the values
before plan optimization; this result is attributed to the long operation time
before optimization. (2) After the implementation of the optimized plan, the
surrounding rock deformation is mainly concentrated in the first primary
support layer stage, where the generated deformation accounts for approximately
70% of the total deformation; After the implementation of the second primary
support layer and the inverted arch, the deformation rate decreases drastically
and is within 0.8~1 mm/d before the secondary lining pouring.
