How to Deal with Washout Problems of Tunnels? Causes and Treatment Methods of Washout

Time:2023-03-25From:sinorock View:

Most mountainous roads inevitably need to pass through tunnels. Washout damage disasters often occur in road tunnels. Different washout problems have different degrees of damage. It is necessary to evaluate the safety of the tunnel structure and take corresponding methods to deal with it. The following will introduce you causes and treatment methods of tunnel washout damage.
washout pipe roof

1. Washout Reasons of Tunnel

① Washout of Tunnel Portal

Landslides and mudslides will occur above and near the tunnel portal, most of which are caused by continuous rainfall or heavy rainfall infiltrating into rocks, causing the accumulation to be saturated and destroying the tunnel portal. There is also a possibility that because the portal is located on a weak foundation, the portal is hollowed out under the condition of continuous rainfall, and the bearing capacity is lost, thus the whole tunnel portal becomes unstable and tilts or collapses.

② Washout in Tunnel

When the tunnel passes through the karst stratum or the karst-developed section, water gushing and mud outburst are prone to occur in the tunnel. In the case of continuous heavy rainfall, the shallow buried section of the natural gully on the surface will be eroded and the surface will be penetrated, causing the tunnel structure to be unable to withstand the water pressure, the waterproof layer will be broken, and the surface water will seep into the tunnel from the weak point.
pipe umbrella

2. Washout Damage Treatment Method

① Survey on the Degree of Washout Damage

It is necessary to investigate the degree of damage of the tunnel and the site conditions first, and to warn and reinforce the parts that are severely damaged and affect traffic safety. According to the survey results, the damage degree of the water-damaged tunnel is evaluated in five states: intact, slightly damaged, moderately damaged, seriously damaged and dangerous.

② Clean Up the Drainage System

If the tunnel is destroyed by debris flow or causes the tunnel to be blocked, the collapsed earth, rock and silt need to be dealt with first. If there is accumulated water in the tunnel, it is necessary to check whether the drainage system is cleaned, and the combination of clearing and dredging drainage is used to discharge the accumulated water and blocked silt out of the tunnel.

③ Top Diversion

If linear or strand-like water seepage occurs at the top of the tunnel, and the lining surface or buried pipe drainage is required at the construction joint position, and when there is partial leakage on the lining surface, it is necessary to paint on the mild slow seepage surface of the vault. Leakage caused by insufficient compactness inside the concrete needs to be plugged with shallow hole grouting to stop the water.

④ Pipe Umbrella

Under normal circumstances, the geology of tunnel entrances where water damage occurs is relatively loose and difficult to support. It is necessary to use self-drilling pipe umbrella for support to bond the broken rock formation with anchor rods and cement slurry to improve the bearing capacity of the rock formation. Self-drilling pipe umbrella is a simple, reliable and practical construction method that can replace conventional pipe umbrellas, especially suitable for collapse-prone formations that are prone to water damage. Washout to tunnels is a common disease in expressway engineering. Safety and driving safety are seriously jeopardized, and the causes of water damage are often related to the local climate, rainfall, and geological conditions around the tunnel. In case of tunnel water damage, the self-drilling pipe umbrella support method can be used for reinforcement after preliminary treatment to stabilize the bearing capacity of the tunnel opening. If you have any support problems related to water damage projects, please consult the Sinorock team, and we will customize the support plan for the self-drilling pipe umbrella for you.

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