过灰堤盾构电力隧道实测沉降规律和机理分析

Measured Settlement Regular and Mechanism Analysis of Shield Cable Tunnel Through Ash Dam

[目的]根据灰堤实测沉降数据分析了实测沉降与一般规律的异同点,研究了灰堤沉降的规律和机理。[方法]介绍了盾构施工引起沉降的一般规律,通过盾构掘进穿越灰堤实测沉降曲线研究了灰堤沉降规律,并与数值模拟沉降规律、一般规律做了对比分析,分析了灰堤沉降突变原因,得出了灰堤沉降机理。[结果]研究表明:灰堤抛石块头较大且不均匀,粘结力差、空隙大,隧道开挖时很难均匀开挖,容易造成超挖和欠挖现象,这是灰堤沉降与一般沉降规律差异原因所在;盾构机过后各测点同时向隧道掌子面方向快速滑移,有外部因素引起地层变形突变,实测规律与一般规律明显相悖;灰堤抛石重组,导致地层向掌子面滑移,得出灰堤地表沉降机理,表明灰堤加固对盾构安全施工至关重要。[结论]研究成果可为其他类似工程提供参考。

[Introduction] The paper aims to research the settlement regular and mechanism of the ash dam according to the similarities and differences of measured settlement and conventional settlement regular analysing results.[Method] Firstly,the conventional settlement regular and mechanism of shield construction were introduced in details.Secondly,the settlement regular of the ash dam was researched by the measured settlement curve of the tunnel through the ash dam,and the measured settlement,numerical simulation of settlement and conventional settlement regular were comprised and analysed.Finally,the causes of the sudden change of the settlement of the ash dam were analysed,and the settlement mechanism of the ash dam was obtained.[Result] The results show that the stone riprap of ash dam is large and uneven,its cohesive force is poor,and its gap is large,thus lead to shield excavate difficulty and easy to cause over-excavation and under-excavation,which is the reason for the difference between ash dam settlement and general settlement law.After the shield tunneling,all the measuring points are sliding towards the tunnel palm face rapidly,shows that there are some external factors causing formation deformation and mutation,the law of actual measurement is obviously inconsistent with the general law.The recombination of ash dam stone riprap structure causes the stratum to slip to the palm face,the surface subsidence mechanism of ash dam is obtained.The results of this paper also show that the ash dam reinforcement is very important to the shield construction safety.[Conclution] The research results can provide references for other similar projects.