Sajith Gangadharan CSP®, MS OSH.’s Post

Flooding is a major ground risk in tunnel construction, as unexpected water ingress can destabilise excavation, delay progress, and endanger safety. Thorough ground investigation is essential to identify groundwater levels and potential water-bearing zones, allowing engineers to plan effective water control measures and reduce the risk of flooding. Probing ahead of the tunnel face is also a reliable method to detect potential water before excavation, enabling timely adjustments to tunnelling methods. Follow us at Tunnel Engineering #flooding #tunnelflood #tunnelcollapse #tunnelcourse #tunnellingcourse #tunnellingpage #tunelfuturistico #tunelizacion #tunelfuturistico #tunnelengineering #safety #tunnel #tunnel #tunnelling #tunneling #tunel #civilengineering #miningengineering #learntunnelling #geotechnicalengineering #geologist #undergroundconstruction #undergroundspace #undergroundproject #tunellingtechnique #tuneldeviento #tünel #túnel #tunneleducation

🚨 Flooding in Tunnels: Challenges, Causes, and Prevention 🚨 Flooding in tunnels is a growing concern for infrastructure resilience and public safety. From transportation hubs to utility passages, flood risks are amplified by extreme weather events and inadequate drainage. Here’s a quick dive into the causes, impacts, and ways to keep tunnels safe and dry: 🔍 Key Causes: 1️⃣ Extreme weather (storms, heavy rainfall) 2️⃣ Poor drainage design or maintenance 3️⃣ Rising groundwater levels 4️⃣ Nearby water bodies (rivers, seas) 5️⃣ Structural failures or water main breaks ⚠️ Impacts: Infrastructure damage and costly repairs Electrical system and operational disruptions Serious safety risks for occupants 🛠️ Prevention & Mitigation: Advanced drainage and regular maintenance Waterproofing tunnel linings and sealing cracks Installing flood barriers and gates Automated pumps and remote monitoring Emergency preparedness and evacuation planning With climate change driving more extreme weather, proactive flood management in tunnels has never been more critical. By investing in resilient design and tech-driven monitoring, we can protect our tunnels and ensure their safety for years to come! #Infrastructure #FloodManagement #TunnelSafety #CivilEngineering #Resilience #civil

Water control: Excess water can lead to flooding, making areas unsafe for workers and machinery. A proper dewatering plan ensures areas remain safe and accessible, preventing accidents and hazardous conditions.

Water ingress into tunnels is a common challenge during construction, particularly in areas with high groundwater levels. Water entering the tunnel can compromise structural integrity, cause delays, and increase costs. Several methods can be used to control water, but pre-excavation grouting is among the most effective. This technique requires thorough ground investigation prior to construction and probing ahead of the tunnel face during excavation to identify water sources. The ground is then treated with an appropriate grouting technique before the excavation of that area. If pre-excavation grouting is not possible or proves unsuccessful, other methods can be employed during construction, depending on the geological and hydrogeological conditions. Post-excavation grouting is a common alternative but can take longer to stop water ingress. It often requires a specially designed grout mix tailored to the ground conditions and water flow. Multiple attempts may be necessary, as water can stop in one location but reappear elsewhere in the tunnel. Dewatering is another method to reduce groundwater levels around the tunnel, effective in certain conditions, particularly soft ground with high groundwater levels. However, this approach may have environmental impacts, which can be mitigated through careful planning and management. Feel free to reach out if you need tunnelling advice for your project during the design, planning or construction. Video credit: Khezr Mohammadamini #tunneleducation #tunnellingpage #tunelfuturistico #tunelizacion #tunelfuturistico #watermanagement #grouting #dewatering #tunnelengineering #artoftunnelling #tunnel #tunnelengineeringisthefuture #tunnel #tunnelling #tunneling #tunel #civilengineering #miningengineering #knowledge #learntunnelling #t #geotechnicalengineering #geologist #undergroundconstruction #undergroundspace #undergroundproject #تونلسازی #tunellingtechnique

🚧 Lets understand the fine lines between Real-Time Probing and Pre-construction investigation ❗ The Key to Water Ingress Prevention in Tunnels.👇 Share your views ▶️ While pre-construction investigations, including geophysical test methods, can provide only a general idea for planning, estimations, tendering and design, they fall short in preventing water ingress, as this is a factor of specific joint gaps opening up at the tunnel crown, walls or invert and alignment driven. ▶️ Therefore, there is no substitute for real-time probing, face mapping, and 3D logging and it's scientific interpretation during tunnel excavation to identify where ground treatment by grouting is needed. ▶️ Based on probe hole observations, cement grouting before blasting is a much easier and safer way to prevent water ingress in tunnels than attempting it afterward. It is more advantageous to know specific vulnerable locations rather than having a general understanding. Tunnel Engineering Tunnelling Association of India ITA-AITES #tunnel #geologist #geology #enginers #designers Metro Rail News The Metro Rail Guy NBM&CW Construction World

True, pre-grouting is a very efficient way to hinder water ingress in underground spaces and true, water ingress points tend to shift due to grouting. To achieve a dry rock space it usually requires grouting, drainage and shotcrete. By implementing efficient measures under construction phase you reduce costs under construction phase but more importantly you reduce costs under operating phase. The ultimate goal is to provide a sustainable construction that is safe and requires minimal maintenance

The primary geotechnical challenge affecting the project area is liquefaction, which leads to the loss of soil strength during seismic activity

Reflections on Tunnel Collapse: Causes and Lessons this is a video of a tunnel collapse during construction, and it’s a sobering reminder of the complexities and challenges we face in our field. The video outlines several key reasons for such failures: Geological Instability: Weak or fractured rock formations can lead to serious stability issues. Engineering Shortcomings: Poor design or inadequate support systems can compromise the tunnel’s integrity. Material Quality: The use of subpar or deteriorating materials can be a major factor. Natural Disasters: Events like earthquakes and floods can disrupt even the most well-planned projects. Human Error: Mistakes in planning, execution, or maintenance can significantly contribute to failures. These points underscore the critical need for rigorous inspections, advanced monitoring, and adherence to strict safety protocols. As professionals in the field, it’s crucial for us to learn from such incidents and continuously improve our practices to ensure the safety and reliability of our projects. It’s a reminder of how vital our role is in safeguarding infrastructure and the importance of never becoming complacent. Video Rights: Respective owners. #TunnelConstruction #Engineering #Safety #Infrastructure #ProfessionalGrowth #civilengineering

Tunnel collapses....reasons Tunnel collapses can result from geological instability, poor engineering, or inadequate construction materials. Geological factors include weak or fractured rock formations, leading to instability and eventual collapse. Inadequate design, such as improper support systems or insufficient reinforcement, can compromise tunnel integrity. Construction materials that deteriorate over time due to environmental conditions or subpar quality may contribute to collapses. Natural disasters like earthquakes and floods also pose significant risks. Human error, whether in planning, execution, or maintenance, can amplify these issues. Regular inspections, advanced monitoring systems, and strict adherence to safety protocols are crucial to preventing tunnel collapses and ensuring the longevity and reliability of underground infrastructure. video rights : Respective owners DM for removal/rights #tunnelling #tunnel #tunnelconstruction #engineering #civilconstruction #civilengineering #construction #engenharia #engenhariacivil #mechanicalengineering

Cornerstone Earth Group, Inc. performed a geotechnical investigation to provide design and construction recommendations, including temporary shoring and dewatering recommendations, for the 𝗖𝗶𝘁𝘆 𝗼𝗳 𝗠𝗲𝗻𝗹𝗼 𝗣𝗮𝗿𝗸’𝘀 𝗖𝗵𝗿𝘆𝘀𝗹𝗲𝗿 𝗣𝘂𝗺𝗽 𝗦𝘁𝗮𝘁𝗶𝗼𝗻 improvements. The project consists of a new stormwater pump station wet well, approximately 35 feet deep, which drains 297 surface acres. Originally built in 1958, the previously existing pump station was designed to protect the area from potential surface flooding that would result from a rainfall event with a 10-year return period (average time between rain events of equal or greater magnitude). The site is geotechnically challenging based on the proximity of the San Francisco Bay (e.g., shallow groundwater) and the potential for soft and weak subsurface materials including Bay Mud. The depth of the excavation posed challenges for temporary shoring and dewatering including internal bracing for the shoring and several well points for dewatering.   For the current project, Menlo Park elected to pursue a new facility designed to provide the area with protection from potential surface flooding due to a rainfall event with a 100-year return period. Increasing the level of service from the 10-to-100-year event requires greater wet well capacity (i.e., footprint) and three pumps of a larger size. Additionally, the new pump station design includes the ability to discharge flow against rising water levels in San Francisco Bay associated with sea level rise and will be 24 inches above the Federal Emergency Management Agency (FEMA) designated 100-year base flood elevation, complying with the sea level rise zoning requirements for the area.