盾构隧道临近河流始发及过电塔掘进技术
Excavation technique of shield launching crossing adjacent river and under-passing voltage tower

为研究多因素状态下，不同类型的风险源相邻时在盾构开挖施工中的相互影响，解决相邻风险源工况下的盾构始发风险问题，以成都地铁3号线盾构隧道工程为背景，总结已穿越地段的沉降数据，分析不同类型的施工风险并确定风险响应措施。采用三维数值方法模拟地铁盾构穿越高压电塔掘进施工工况，通过改变前方开挖土体的性质来模拟渣土改良的过程和地面加固措施，通过改变材料属性来模拟注浆材料强度随时间的变化过程，分析渣土改良、洞内注浆和地面注浆措施对盾构隧道穿越建筑物的影响，并进行数值计算假设的可行性和参数取值的合理性验证。研究结果表明：在盾构始发前需进行地面降水、河流防水铺砌与河堤加固等措施，在盾构始发后至下穿河流掘进前需进行洞门密封、渣土改良和土仓置换等措施，在穿越河流后应及时进行电塔的洞内注浆、地面加固和掘进参数的优化调整等措施，一系列针对相邻风险源施工的辅助措施，证明了该盾构掘进技术成果的可行性；在下穿建筑物施工时应关注已开挖环处的地表沉降，并加强管片脱出盾尾时所在断面的地表沉降趋势的监控；在渣土改良和有效优化掘进参数的基础上，采用洞内施工措施和地面加固均可有效控制地层沉降，但洞内注浆等措施优于地面加固效果。提出的盾构临近河流始发及下穿电塔建筑物的施工措施和综合掘进技术，可为多风险源下临近的盾构施工提供理论依据和指导措施。
In order to study the interaction between different kind of adjacent risk sources under multi-factors, and solve the risk problem of shield launching under the condition of adjacent risk sources, on the basis of the shield tunneling of Chengdu Metro Line 3, settlement data of the excavated section were summarized. Different types of construction risk were analyzed and the risk response measures were also determined. Moreover, a three-dimensional numerical simulation of the metro shield tunneling construction was conducted, in which the soil improvement and ground reinforcement were simulated by changing the property of soil in front of the TBM, and the variation of the strength of grouting material along with time was simulated by changing the material properties. Influence of soil improvement, grouting in tunnel, and ground grouting on shield tunneling crossing constructions was analyzed. Calculation result verified the feasibility of the numerical calculation hypothesis and the rationality of the selected parameters. A series of auxiliary measures for the construction of adjacent risk sources proved the feasibility of the shield tunneling technological achievements. The specific measures included surface precipitation, waterproof paving of river and embankment reinforcement before shield launching, hole sealing, soil improvement and soil replacement of warehouse before crossing the river and after shield launching, the underground grouting of electric tower, ground reinforcement and optimization of tunneling parameters after crossing the river. The results show that attention should be paid to ground settlement of the excavated rings in the construction of shield tunneling under buildings and the monitoring of the trend of ground settlement in the section where the segments are coming off the shield tail should be enhanced. Based on the soil improvement and effective excavation parameters, underground construction measures and ground reinforcement both can effectively control the ground