偏压隧道病害特征及其控制措施

Study on disease characteristics of unsymmetrcial pressure tunnel and its control measures

通过案例收集和资料统计分析,研究了造成隧道偏压的原因及偏压对隧道衬砌结构的危害,分析了应考虑偏压作用的临界埋深的影响因素及其规律,揭示了偏压控制措施的原理。结果表明:造成隧道偏压的原因有地形、地质和施工3个方面,而地形是主要因素,特别是在洞口浅埋地段;偏压使得衬砌结构和围岩受力不对称,更易发生剪切破坏和整体失稳;临界偏压埋深与隧道跨度、围岩条件、地表坡度有关,跨度越大、围岩越差、坡度越陡,则临界埋深越大;治理偏压应从减小偏压程度的角度出发,综合采取地表和洞内的控制措施,如偏压回填、偏压挡墙、预应力锚杆和半明半暗结构等。

Through cases collection and statistical analysis,causes and hazards of unsymmetrical pressure tunnel were studied.Influence factors of critical depth of unsymmetrical pressure tunnel were analyzed as well as principle of control measures.Results show that causes of unsymmetrical pressure tunnel are terrain,geology and construction.The terrain is major factor,especially in shallow cover section of tunnel entrance.It is more susceptible to occur shear failure and overall unstable failure due to unsymmetrical pressure acting on lining and surrounding rock.Critical depth is proportional to rock condition,tunnel span and surface gradient.In view of reducing degree of bias,comprehensive measures are taken both on ground surface and inside tunnel,such as backfill bias,bias retaining walls,pre-stressed anchor and half-light structure.