深厚冲积层冻结井筒可靠性的模糊随机灵敏度分析模型

Fuzzy random sensitivity analysis model for reliability of freezing shaft lining structure in deep alluvium

可靠性灵敏度分析对深部地下工程的施工安全至关重要。在模糊随机可靠性理论的基础上,将常规的灵敏度分析模型进行模糊随机优化,获得模糊随机可靠性灵敏度的均值和标准差的数值计算模型。根据深厚冲积层冻结井筒结构抗力和荷载的模糊随机分析,综合考虑各变量参数的不确定性,建立土层埋深、冻结温度、混凝土抗压强度、土体含水量、井筒厚径比、冻结壁厚度和配筋率对深厚冲积层钢筋混凝土井筒结构可靠性的模糊随机灵敏度分析模型。工程算例表明,优化后的模糊随机灵敏度以模糊区间值表示各参数对钢筋混凝土冻结井筒整体结构可靠性的影响程度,比传统灵敏度的定值表征方式更具有工程合理性。此外,通过对比各参数的模糊随机灵敏度数值计算结果可知,影响深厚冲积层钢筋混凝土井筒可靠性的主要因素,按重要程度依次是土层埋深、冻结温度、混凝土抗压强度、土体含水量、井筒厚径比、冻结壁厚度和配筋率。同时,模糊随机灵敏度分析还具有正负符号特征,说明在实际工程中土层埋深、混凝土抗压强度、土体含水量、井筒厚径比和配筋率与井筒可靠性呈同向变化关系,而冻结温度和冻结壁厚度与井筒可靠性则呈反向变化关系。

Reliability sensitivity analysis is very important to construction safety of deep underground engineering.On the basis of fuzzy random reliability theory,conventional sensitivity analysis model was optimized with fuzzy random optimization,and numerical calculation model of mean and standard deviation of sensitivity of fuzzy random reliability was obtained.According to deep alluvium freezing shaft structure resistance and load of fuzzy random analysis,comprehensively considering the uncertainty of variable parameters,a fuzzy random sensitivity analysis model was established of soil depth,soil freezing temperature,concrete compressive strength,water content,wellbore thickness to diameter ratio,reliability of thickness of freezing shaft lining and reinforcement ratio to deep alluvial layer reinforced concrete shaft structure.Engineering examples have shown that optimized fuzzy random sensitivity represents the influence degree of each parameter on reliability of whole reinforced concrete freezing shaft lining structure with fuzzy interval value,which is more reasonable than traditional evaluation method of sensitivity.In addition,by comparing numerical results of fuzzy random sensitivity of each parameter,it can be seen that main factors affecting reliability of reinforced concrete wellbore in deep alluvium are,in order of importance,depth of soil layer,freezing temperature,compressive strength of concrete,soil moisture content,thickness-diameter ratio of freezing shaft lining,thickness of freezing shaft lining,and reinforcement ratio.Meanwhile,fuzzy random sensitivity analysis also has positive and negative sign characteristics,which indicates that depth of soil layer,compressive strength of concrete,water content of soil,thickness-diameter ratio,and ratio of reinforcement have the same change relation with reliability of freezing shaft lining structure,while freezing temperature and thickness of freezing shaft lining have opposite change relation with reliability.