相依性条件下滨海软土隧道盾构施工渗漏水风险评价

滨海地区多为海相和湖相沉积的软土,施工难度大,渗漏水病害多发,因此,应对盾构施工过程的渗漏水风险进行评价来保证隧道安全施工。构建渗漏水风险评价三级指标体系,将云模型与Copula函数结合,基于Copula函数对于风险指标中相关风险因素的相依性处理,云理论对于定性与定量概念的处理与转换优势,构建相依性条件下的二维和三维云-Copula模型。以宁波市轨道交通1号线为例,利用云-Copula模型计算二级指标对于各个风险等级的隶属度,确定危险性较大的二级指标为注浆质量、止水条、衬砌混凝土自防水。利用D-S证据理论进行证据融合确定该检测区段渗漏水病害的风险状态为安全,但有向基本安全状态发展的趋势。通过对危险性较大的指标加强监控,使渗漏水得到有效控制,为软土盾构隧道施工过程中渗漏水病害的风险评价与管理提供了一种新的方法。

Risk Assessment of Leakage Water in Shield Construction of Coastal Soft Soil Tunnel under Dependent Condition

The coastal areas are mostly soft soils with marine and lacustrine deposits,which results in difficult construction due to serious leakage of water. Therefore,the risk of leakage water in the shield construction process should be evaluated to ensure the safe construction of the tunnel. This paper constructs a three-level indicator system for risk assessment of leakage water,combines the Cloud model with Copula function. Two-dimensional and three-dimensional Cloud-Copula models are constructed based on the Copula function to treat dependently the related risk factors in risk indicators,and on the Cloud theory's advantages in the treatment and conversion of qualitative and quantitative concepts. With reference to Ningbo Rail Transit Line No. 1,the Cloud-Copula model is used to calculate the degree of membership of the second-level indicators for each risk level,and the more dangerous second-level indicators are determined to be grouting quality,sealing strips,and lining concrete waterproof. The D-S evidence theory is used to carry out evidence fusion to determine the risk status of leakage water damage in the detection zone,but there is a trend toward the development of basic safety status. By strengthening the monitoring of the more dangerous indicators, the leakage water can be effectively controlled,providing a new method for risk assessment and management of leakage water in the construction process of soft soil shield tunnels.