[最新文献]应变软化岩体中开挖隧道的损伤区厚度和壁面收敛性评估[12/09/2020]

1 论文

Assessment of damage zone thickness and wall convergence for tunnels excavated in strain-softening rock masses 应变软化岩体中开挖隧道的损伤区厚度和壁面收敛性评估

Highlights

•There is a relation within damage zone thickness and tunnel convergences.

•"Convergence constant" can be used to prediction of tunnel convergences.

•Highly damaged zone thickness can be found reliably with empirical analysis.

•HDZ thickness has found in range 4.5–7.5 m for weak to fair quality rock masses.

Abstract: There are two fundamental issues in all underground excavations, which are safety and economy. To ensure safety and expedite excavations, level of tunnel wall convergences and damage zone thickness should be predicted before the excavation starts, should be determined accurately, and monitored during the excavation by the tunnel designer. However, accurate prediction of these two parameters is difficult unless in-situ stress and deformation measurement tools are used. In this study, damage zone thickness and tunnel wall convergence relation was investigated for horseshoe-shaped highway tunnels by using empirical methods. For this aim two-dimensional plane strain finite element models were used. Totally 9 tunnel sections were selected for the empirical analysis from 5 different ongoing tunnel excavations, which are excavated in weak and fair quality rock masses and show strain softening post-failure behavior. With the help of data gathered through in-situ convergence measurements and predicted convergences and rock mass geotechnical properties an empirical analysis was conducted. Engineering characteristics of the tunnel routes were determined by means of geological mapping, drillings and laboratory studies. Tunnel wall convergences were measured by optical measurement devices in three-dimensional space. Then, numerical models have been created for each of the tunnel sections studied. For evaluation of damaged zone thickness; yielded elements, volumetric strain, and principal stress concentrations have been used. Damage zone thickness and convergences were estimated from the numerical models and the whole data were compared with the real convergence results. Findings have been compared with previous researchers’ convergence predictions and plastic zone calculation approaches. The results are in agreement both with the field measurements and previous empirical approaches. In this way, an empirical relation has been obtained for tunnel wall convergences and damage zone thicknesses. Besides, through an analysis of the relations of convergences at each query points in plane strain finite element model, a new empirical relation has also been put forth that gives "Convergence Constant" for modelled cross-section. This constant can be used as an auxiliary tool for prediction of next section convergences, on the condition that excavation has similar geological, geotechnical properties and topography.

Keywords: Convergence, Excavation damaged zone, NATM, Strain-softening rock, Tunnel, Turkey

摘要：在所有的地下开挖工程中，有两个基本问题，那就是安全和经济。为了保证安全和加快开挖速度，隧道壁收敛水平和破坏区厚度应在开挖开始前进行预测，应准确确定，并在开挖过程中由隧道设计人员进行监测。然而，除非使用原位应力和变形测量工具，否则很难准确预测这两个参数。本研究采用经验方法研究了马蹄形公路隧道的损伤区厚度与隧道壁收敛关系。为达到此目的，采用二维平面应变有限元模型。从5个不同的在建隧道开挖中共选取了9个隧道断面进行实证分析，这些断面开挖于软弱和质量一般的岩体中，表现出应变软化后的行为。借助于通过原位收敛测量和预测收敛的数据以及岩体岩土特性收集的数据进行了实证分析。通过地质测绘、钻探和实验室研究确定了隧道路线的工程特征。通过三维空间的光学测量设备对隧道壁的收敛性进行了测量。然后，为研究的每个隧道段建立了数值模型。为了评估破坏区厚度，采用了屈服元素、体积应变和主应力集中。破坏区厚度和收敛性从数值模型中估计出来，并将整个数据与实际收敛结果进行比较。研究结果与前人的收敛预测和塑性区计算方法进行了比较。结果与现场测量结果和以往的经验方法都是一致的。通过这种方式，得到了隧道壁收敛与破坏区厚度的经验关系。此外，通过对平面应变有限元模型中各查询点收敛关系的分析，还提出了一个新的经验关系，给出了建模截面的 "收敛常数"。该常数可以作为辅助工具，在开挖的地质、岩土性质和地形相似的条件下，预测下一断面的收敛性。

2 相关文献

Note: '相关文献' 是按照Google的排序算法产生出来的.

[1] A study of damage and disturbance from tunnel excavation by blasting and tunnel boring

[2] Assessment of plastic zone thickness and convergences for tunnels excavated in weak to fair quality rocks in turkey

[3] Behaviour of Blast-Induced Damaged Zone Around Underground Excavations in Hard Rock Mass

[4] Modified criterion for prediction of tunnel deformation in non-squeezing ground conditions

[5] Groundwater Effect on Faulted Rock Mass: An Evaluation of Modi Khola Pressure Tunnel in the Nepal Himalaya

[6] Tunneling under squeezing conditions : Effect of the excavation method

[7] Stress induced problems in Himalayan tunnels with special reference to squeezing

[8] Support for very weak rock associated with faults and shear zones

[9] Guide to Cavern Engineering

[10] Permeability measurements in the excavation damaged zone in the opalinus clay at mont terri rock laboratory, switzerland

[11] Technical Manual for Design and Construction of Road Tunnels — Civil Elements

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