雄安新区地下空间利用地质安全风险评价

Geological safety risk assessment of underground space utilization in Xiongan New Area

地质环境是地下空间的承载体,明显制约地下空间开发利用。识别地下空间利用的地质安全风险及其主要影响要素可为地下空间合理规划、地下空间设施安全保障提供科学依据。以雄安新区为例,从空间、资源、环境、灾害4个层面,分析了不同类型地质安全风险隐患,遴选含水砂层厚度、土体承载力特征值、土体压缩模量、地面高程、地下水位埋深、地面沉降速率和砂土液化指数等定量指标,构建指标体系进行地质安全风险评价。针对现有评价方法在客观赋权方面存在的不足,在考虑数据相关性、离散性和相对性(冲突性)的基础上,引入基于指标相关性的指标权重确定法(criteria importance through intercriteria correlation,CRITIC),提出了CRITIC-Entropy组合确权法,使得赋权更为科学与合理。研究结果表明,雄安新区地下空间地质安全风险呈现出深部层位小于浅部层位的特征,且Ⅰ级和Ⅱ级风险区主要位于白洋淀及周边、南张镇东和大营镇东等区域,浅层(0~15 m)、次浅层(15~30 m)、次深层(30~50 m)、深层(50~100 m)地下空间Ⅰ级和Ⅱ级风险区累计面积占比分别为54.49%、42.51%、41.06%和42.18%。不同层位地下空间地质安全风险的主要影响要素有所差异,总体来说,土体压缩模量、土体承载力特征值、地面高程和地下水位埋深影响权重较高。同时,需要关注地面沉降、地下水位动态演变和不同施工方式引起的风险变化。成果可为雄安新区地下空间利用规划科学优化和防灾减灾提供地学依据,也可为其他地区相关研究提供借鉴。

The utilization of underground space is related to geological environment.Identifying the geological safety risk and their influencing factors of underground space utilization can provide scientific basis for underground space management and the safety of underground space facilities.Previous studies have utilized various methods including analytic hierarchy process(AHP),fuzzy mathematics,and neural network to analyze the geological environment conditions of urban underground space.However,their methods have limitations in terms of objective weighting.To address this,considering the data correlation,discreteness,and relativity(conflict),an improved analytic hierarchy process incorporating the criteria importance through intercriteria correlation(CRITIC)method was introduced.The CRITIC-Entropy combination weighting method,which made the weights more scientific and reasonable,was proposed to evaluate the geological safety risk of underground space utilization.In Xiongan New Area,the geological safety risks related to stress variation,bearing capacity,submergence and anti-floating,soil pressure change,and sand liquefaction were analyzed.The evaluation focused on four aspects:space,resources,environment,and disaster.Quantitative indicators,such as aquifer thickness,characteristic value of soil bearing capacity,compression modulus of soil,ground elevation,buried depth of groundwater level,land subsidence rate,and sand liquefaction index were selected to construct the geological safety risk evaluation index system for shallow(0−15 m),sub-shallow(15−30 m),sub-deep(30−50 m),and deep(50−100 m)underground spaces.The study reveals that the geological safety risk of underground space in the study area follows a pattern that deep layers have a lower risk compared to shallow layers.The areas withⅠandⅡrisk grades are predominantly located at Baiyangdian and its surrounding areas,east of Nanzhang town,and east of Daying town.The cumulative acreage ofⅠandⅡrisk grades in shallow,sub-shallow,sub-deep,and deep underground space accounts for 54.49%,42.51%,41.06%,and 42.18%,respectively.Additionally,the dominant factors influencing the geological safety risk vary across different layers of underground space,while compression modulus of soil,characteristic value of soil bearing capacity,ground elevation,and buried depth of groundwater level show high weights.It is also important to consider the risk changes caused by the potential changes of land subsidence rate,buried depth of groundwater level,and different excavation ways in the future research.These findings provide a geological foundation for the scientific optimization of underground space utilization and disaster prevention and mitigation in Xiongan New Area and other similar areas.