隧道施工“关门”式灾害及其成因初步分析

Preliminary Analysis of Causes of Closing Type Blockage Disasters during Tunnel Construction

文章在对隧道施工"关门"式灾害调查及隧道施工"关门"式灾害与隧道施工地质灾害关系分析的基础上,提出了7种围岩变形失稳塌方致灾构造、6种突泥致灾构造和2种隧道洞内泥石流致灾构造,并对其致灾成因进行了分析。结果表明:围岩变形失稳塌方致灾构造位置的围岩级别未据实修正、初期支护未及时施作或初期支护强度不足,导致围岩变形失稳塌方;自体隔泥土盘或复合隔泥岩土盘的厚度不足、强度过低或突泥致灾构造条件变化等造成隔泥岩土盘被突破,导致突泥和泥石流;隔泥节理裂隙化岩盘沿优势结构面剪裂破坏导致突泥;隧道施工爆破震动导致岩溶中充填的粘土瞬间下坐,隔泥岩盘被突破致使突泥。

Based on investigation of closing type blockage disasters and analysis of their relationship to geological disasters, seven structures affected by deformation-induced collapse of the surrounding rock, six structures affected by mud bursts and two structures affected by debris flows inside the tunnels are introduced, and the causes of the disasters are analyzed. The examination shows that： 1） the grade of the surrounding rock where the instability occured due to deformation and collapse were not corrected and either the primary supports were not constructed in time or the the primary support was not intense enough; 2） the soil disc of the soil-isolating rock was broken through be- cause the autologous mud isolating soil disc and compound soil disc were not thick enough or strong enough, or the conditions of the disasters causing mud bursts varied, which led to mud bursts and debris flows; 3） shear fracture failure occurred along the preferred structure planes at mud-isolating joint fractured rock discs and led to mud bursts; and 4） vibrations induced by tunnel construction resulted in instantaneous sinking of clay fill in karst caves and caused mud-isolating rock discs to break and mud bursts to occur.