ENGINEERING STRUCTURES AND GEOLOGICAL INVESTIGATION

• Site investigation - aims to determine the suitability of the site for the intended purpose, identify potential geologic hazards, and determine the soil and rock properties that may affect the design and construction of the project.
• In-Situ Testing - Helps to obtain a better understanding of the characteristics and behavior of soil and rock at the actual site conditions.
• Foundation design - the foundation of any structure is critical to its stability and safety.
• Slope stability analysis - involves studying the soil and rock properties, geologic structure, and ground water conditions to assess the potential for slope failure and i dentify measures to prevent or mitigate it.
• Ground improvement - the alteration of site foundation soils or project earth structures to provide better performance under design and/or operational loading conditions.
• Environmental impact assessment - involves identifying and analyzing the potential environmental hazards associated with the project and designing measures to minimize or mitigate these impacts.
• Dams - is a barrier constructed across a river or other waterway to hold back and control the flow of water, creating a reservoir behind it.
• Reservoir - an enlarged natural or artificial lake, storage pond created using a dam to store water.
• Enbankment Dams - constructed from natural materials such as soil, clay, and rock. They are often used to store water for agricultural or municipal purposes
• Gravity Dam - a structure designed to withstand loads by its own weight and by its resistance to sliding and overturning on its foundation.
• Arch Dam - designed so that the force of the water against it presses against the arch, causing the arch to straighten slightly, strengthening the structure as it pushes into its foundation.
• Rock-fill Dam - mainly made from dumped and compacted rock fill. The impermeable parts are usually made of reinforced concrete, asphaltic concrete or clay.
• FACTORS INFLUENCING DAM DESIGN AND CONSTRUCTION

  • Topography and Geology
  • Hydrology and water management
  • Climate and weather conditions
  • Seismicity and earthquake hazards
  • Environmental and social factors
  • Site investigation and geological considerations
  • Geology and rock mass properties
  • Geological structures
  • Seismic hazards
  • Soil and rock properties
  • Groundwater conditions
  • Construction materials
• Road Tunnels -These tunnels help cars go through mountains and cities safely
• Rail Tunnels - They let trains travel smoothly through hills and cities.
• Water Tunnels - They bring water to places where it's needed for drinking and making electricity
• Mining Tunnels - They're like underground roads for digging up valuable rocks and minerals
• Underwater Tunnels - They're like secret roads for cars and trains under the ocean or big rivers.
• Circular tunnels - evenly distribute pressure, making them ideal for unstable ground conditions where collapse is a risk.
• Horseshoe tunnels - are stable in solid rock formations, requiring minimal support and excavation, making them efficient and cost effective.
• Rectangular tunnels - are versatile and suitable for urban environments or accommodating specific utilities due to their straightforward design.
• Oval tunnels - offer stability while maximizing usable space, making them suitable for various geological and functional contexts, especially in constrained areas.
• Geological Mapping - involves studying surface rock outcrops, soil types, and geological structures to understand the geological setting of the tunnel alignment.
• Geophysical Survey - utilize techniques such as seismic reflection, electrical resistivity, ground-penetrating radar (GPR), and gravity surveys to investigate subsurface geology.
• Cross section - is a vertical slice through the Earth's surface,showing the arrangement and relationships of rock layers and other geological features beneath the surface.
• Topographical map - represents the three-dimensional featuresof the Earth's surface on a two-dimensional plane, showingelevation and landform contours.
• Structural map - shows the distribution, orientation, and relationships of rock units and geological features like faults and folds.
• Hydrogeological studies - focus on assessing ground water conditions and potential water ingress into the tunnel.
• Borehole logging - involves drilling boreholes along the tunnel alignment and analyzing core samples and geophysical logs.
• Standard Penetration Test (SPT) - is a field test used to determine the strength and density of soil.
• Cone Penetration Test (CPT) - a field test that measures the resistance of soil to penetration by a cone-shaped device.
• Geological modeling - involves integrating geological data

  obtained from various investigation methods to create three dimensional (3D) geological models of the subsurface.
• Importance of Geological Investigation in Bridge Site

  • Foundation Design
  • Site Suitability
  • Risk Assessment
• Factors in Bridge Site Selection

  • Soil Composition
  • Bedrock Quality
  • Seismic Activity
  • Karst Landscapes
  • Water Table and Hydrogeology
  • Geological Hazards
• Geotechnical drilling - involves drilling boreholes into the ground to extract soil and rock samples.
• Seismic surveys - use seismic waves to investigate subsurface geological structures.
• Ground-penetrating radar (GPR) - uses high-frequency electromagnetic waves to image subsurface features.
• Geological mapping - involves the systematic observation and recording of surface geological features, such as rock outcrops, soil types, and geomorphological structures.