**Source**

**SPE Disciplines**

**Theme**

**Author**

**Concept Tag**

- accident (1)
- Accident tree (1)
- Accident tree analysis (1)
- analysis (2)
- block (1)
- collapse (1)
- collapse risk (1)
- construction (1)
- construction process (1)
- crack (1)
- discontinuity (1)
- distribution (1)
- Engineering (2)
- factor (1)
- failure (1)
- fracture (1)
- identification (1)
- investigation (1)
- method (2)
- model (1)
- plane (1)
- process (1)
- reservoir simulation (1)
- risk and uncertainty assessment (1)
- risk factor (1)
- rock (1)
- rock mass (1)
- stability (1)
- statistics (1)
- structure (1)
- theory (1)
- tunnel (2)
- tunnel collapse (1)

**Industry**

**Technology**

**File Type**

Collapses are serious or even disastrous accidents during tunnel construction, which of frequent occurrence. This paper describes a method for assessing the risk associated with collapses in tunnels. The focus is put on collapses which occur in the tunnel constructed by drill and blast method. And the preference is attached to studying their causes and mechanisms and assessing their risk during tunnel construction.

On the basis of an extensive literature search, causes and mechanisms analysis of collapse is carried out. All the potential risk factors related to tunnel collapse are identified. The statistical analysis and the accident tree analysis are carried out to analyze the contribution of each risk factor to tunnel collapse. The importance ranking of risk factors is given. It can be confirmed that precise geological investigation and appropriate construction process are the most effective controllable factors for preventing the occurrence of tunnel collapse. Accident tree analysis is also employed to estimate the probability of collapse occurrence. And the analytic hierarchy process is employed to evaluate the potential loss of collapse. At last a whole approach for tunnel collapse risk assessment is presented.

The collapse of tunnel has been discussed in many papers and textbooks. The Health and Safety Executive (HSE) carried out an investigation after the collapse of Heathrow Express Rail Link Station tunnels, and reported the causes of the collapses as unpredicted geological causes, planning and specification mistakes, calculation or numerical mistakes, construction mistakes and management and control mistakes (Dimitrios K. 2008); Seidenfuß (2006)provides a comprehensive categories for tunnel collapses and analyzes the different causes of collapses as well as their mechanisms on the basis of an extensive literature search; Feng w.x. et al.(2001) presents the causes, the treatment and the treatment effect of collapses through a lot of cases analysis. All the researches show that the uncertainty factors, such as inadequacy of geotechnical information, wrong choice of construction methodology, as well as improper organization of the works, initiate collapses.

How can we lower down these uncertainties to avoid or at least reduce collapses in tunnels in future? One effective way to do so is to understand and control these uncertainties.

ISRM-SINOROCK-2009-174

ISRM International Symposium on Rock Mechanics - SINOROCK 2009

Industry:

- Transportation > Ground > Rail (0.73)
- Transportation > Infrastructure & Services (0.53)

SPE Disciplines: Management and Information > Risk Management and Decision-Making > Risk, uncertainty, and risk assessment (1.00)

Wang, S.H. (Northeastern University) | Guo, M.D. (Northeastern University) | Yang, Y. (Northeastern University) | Wang, Y. (Northeastern University) | Zhang, Y.B. (Northeastern University) | Che, D.F. (Northeastern University)

Numerical analysis provides a useful tool to enhance the understanding of block rock masses. The stability of rock blocks of tunnel or underground opening are commonly analyzed based on rigid body limit equilibrium theory only by considering gravity, while the secondary stress field after excavation of the block is usually not taken into account. Existence of structural planes affects dynamical properties greatly in rock tunnel structures. Especially in hard rock tunnel engineering, the stability of rock is controlled in a sense by the number of blocks, i.e. the size, orientation and locations of the discontinuities. Key-block failures occur where blocks of rock which are separated form the rest of the rock mass by discontinuities slide of fall into an excavation. According to the geometric stochastic block theory and reliability analysis, a new program GeoSMA-3D (Geotechnical Structure and Model Analysis-3D) for simulating tunnel structural planes in rock mass is put forward to develop based on geometric stochastic block theory and modern computer technique. The new model assumed that rock mass consists of blocks, thus formulating a combination of block model. This program adopts vector analysis, which can simulate all excavation planes especially in the tunnel and other underground structure. It can also create three-dimensional structural model and analyze mobility of key-block in the simulation plane by means of geometry and kinematics theory. The distribution of all key blocks and the quantitative data are analyzed by means of the newly developed program. The results show that parts of the blocks’ crown zone are under compressive stress, which gradually increases as the underground opening in Shimian Tunnel, Liaoning, China. It can be concluded that the new program is an effective tool for modeling blocky rock masses.

The design is so far mostly empirical. It assumes that the block is rigid and is located in an otherwise fixed body of rock and bounded by a combination of flat discontinuities and excavation surfaces. In practice these conditions are most likely to be approximated when extensive discontinuities occur in hard rock. In common with most other solutions for three-dimensional blocks, possible block movements are assumed to be limited to translation only, and rotation is excluded. Existence of structural planes affects dynamical properties greatly in rock tunnel structures.

It assumes that the block is rigid and is located in an otherwise fixed body of rock and bounded by a combination of flat discontinuities and excavation surfaces. In practice these conditions are most likely to be approximated when extensive discontinuities occur in hard rock. In common with most other solutions for three-dimensional blocks, possible block movements are assumed to be limited to translation only, and rotation is excluded.

ISRM-SINOROCK-2009-117

ISRM International Symposium on Rock Mechanics - SINOROCK 2009

SPE Disciplines: Reservoir Description and Dynamics > Reservoir Characterization > Exploration, development, structural geology (1.00)

Technology:

- IT > Mathematics Of Computing (0.72)
- IT > AI (0.47)