ABC Engineering is undertaking a challenging underground construction project involving the development of a subway system in a densely populated urban area. The project faces various geotechnical challenges that demand careful consideration and engineering expertise.

Step 1: Site Investigation and Soil Conditions

Site Investigation: Before the commencement of underground construction, ABC Engineering conducts extensive site investigations. This involves soil testing, geological surveys, and geophysical assessments to understand the subsurface conditions.

Soil Conditions: The site reveals complex soil conditions, including heterogeneous soil layers, rock formations, and the presence of water tables. Variability in soil properties poses challenges for tunneling and excavation processes.

Step 2: Tunneling and Excavation Challenges

Rock Excavation: Portions of the tunnel traverse through rock formations, leading to challenges in rock excavation. The type of rock, its strength, and potential geological faults impact the excavation process.

Groundwater Management: The water table proximity requires effective groundwater management strategies during tunneling. Water ingress can jeopardize the stability of excavated areas and increase the risk of sinkholes.

Step 3: Structural Integrity and Settlement Concerns

Structural Integrity: As tunnels are constructed, maintaining the structural integrity of surrounding buildings and infrastructure is crucial. Monitoring ground settlement and implementing support systems are vital to prevent damage to existing structures.

Surface Settlement: The excavation process induces surface settlement, potentially impacting roads, utilities, and nearby buildings. ABC Engineering employs innovative techniques such as compensation grouting to mitigate settlement effects.

Objective Type Question: What is a common geotechnical challenge faced during the tunneling and excavation phase in underground construction?

A) Managing surface settlement

B) Dealing with rock excavation

C) Implementing groundwater management

D) Ensuring structural integrity