Identification and analysis of Swiss National Road tunnels pathologies

Abstract

ABSTRACT:In order to evaluate the general conditions (i.e. safety, serviceability and durability) of tunnels, a detailed analysis of the lining structure and surrounding rock mass is required. During the service life of the tunnel, regular survey activities should be performed to check the tunnel conditions and regular conservation practices are necessary to preserve the tunnel's structural integrity and guarantee safety and serviceability during operation. The collection of data about tunnels since their construction and during their service life may help in the assessment of tunnel conditions and improve the understanding of tunnel degradation with time. The long term behaviour of the Swiss National Road tunnels has been studied and a specific data base has been developed. Based on detailed literature review and analysis of principal inspections results collected in the data base, the main pathologies that affect the Swiss road tunnels have been identified. In addition, by means of a specific data analysis, both degradation potential and rate have been investigated and the main influence factors involved have been selected. The obtained results confirm what was expected according to observations in the past. After a brief introduction about the tunnels of the National Roads network, this paper describes the main steps of the data analysis, different methods used and main results of the analysis. Due to the fact that the tunnels within Swiss National Roads were developed during the sixties, attention has been focused only on concrete lined tunnels. KEYWORDS:Road Tunnels pathologies, Degradation, Data Base, Correspondence Analysis, G.I.S. tools, Maintenance INTRODUCTIONDuring the service life of a tunnel, like any structure, safe and effective operation should be ensured. The tunnel must fulfil its design purposes without creating circulation restraints to normal users or safety problems. Underground constructions have longer service life when compared to other structures and several factors such as material quality and weathering actions may contribute to reduce their durability.The distinctive feature of a tunnel is the direct interaction between the lining and the rock mass. Load conditions may vary significantly with time due to changes in rock mass behaviour and environmental 3 actions. Various chemical, physical and mechanical processes may determine the deterioration of exposed surfaces of the rock mass and the lining. It is possible to distinguish between:• the chemical action, properly named weathering, caused by the chemical interaction of the tunnel with the surrounding environment;• the physical action, ageing, ruled by time dependent changes affecting the characteristics of concrete lining and rock mass;• the other actions, mainly mechanical, such as pore water pressure redistribution, ice and frost, fires and car collisions.All these processes may change the tunnel equilibrium conditions with time (Sandrone and Labiouse, 2010) and contribute to the changes in tunnel serviceability, stability and sa...

Concrete Spalling Detection for Metro Tunnel from Point Cloud Based on Roughness Descriptor

“…It is not uncommon to have damage on the tunnel surface due to the possibility of external forces and material deterioration [1,2]. Therefore, during the service period of a tunnel, regular inspection activities should be carried out to check its health condition and regular maintenance measures should be taken to keep its structural integrity and ensure the safety in the operation process [3].…”

Influence of Existing Defects on Mechanical Properties of NC Lining

“…Because of the complex environment, unclear load characteristics, and construction quality problems, lining cracking, leakage, and other problems become common and are difficult to prevent and treat [1][2][3]. Among them, voids behind the lining and insufficient thickness of the lining are two common tunnel quality defects caused by inappropriate construction, which are one of the main causes of tunnel damage [4,5] and have a serious impact on the safety and durability of the structure [6].…”

Study of the Influence of Train Vibration Loading on Adjacent Damaged Tunnel

“…For the reason that lining structure suffers influences from tunnel site conditions and construction factors, damaging behaviors are commonly observed from construction period to operation period. To ensure the structural stability and safety, more and more attention was paid to the damaging behaviors in the tunnel [1,2]. Moreover, previously published literature demonstrates that crack is the most common outcome of the damaged tunnel lining structure [3][4][5].…”