The Lugeon Test: Methodology, Interpretation, and Applications in Geotechnical Engineering

 The main forces acting on cross drainage works and other hydraulic structures, as described in the sources, include various types of loads and pressures that engineers must account for in design and analysis.

These forces can be categorized as follows:

• Water-Related Forces

  • Water Pressure/Hydrostatic Loading: This is a significant external load. Aqueducts, for example, are designed to withstand the hydraulic forces exerted by flowing water. For box culverts, hydrostatic pressure on the soil at the top and bottom of the box is considered.
  • Uplift Pressure: This force acts on the underside of various hydraulic structures. It is a critical consideration for the floor of aqueducts or siphons, especially when the bottom floor is depressed below the drainage bed (as in siphon aqueducts) or due to seepage of water from the canal to the drainage. Uplift pressure is also a key force acting on gravity dams.
  • Siphonic Action: In structures like syphon aqueducts and canal siphons, the water flows under siphonic action, meaning there is no presence of atmospheric pressure in the natural drain or canal. Syphon aqueducts are designed to handle higher hydraulic pressures effectively.
  • Wave Pressure: This force specifically acts on gravity dams.

• Earth/Soil-Related Forces

  • Soil Load/Pressure: The load from saturated soil can act on the top of structures like box culverts. Soil pressure also acts on the side faces of box culverts and is a general external load on cross drainage works.
  • Silt Pressure: This is a force that acts on dams.
  • Earth Pressure: Wing walls are designed to withstand maximum differential earth pressure.

• Structural and Gravity Forces

  • Self-Weight: The weight of the structure itself, such as the self-weight of the top slab of a box culvert, is a fundamental load. Similarly, the weight of a dam is a force that provides stability.
  • Traffic/Vehicular Loads: Structures like aqueducts can be designed to account for traffic loads if they are combined with roadways. For box culverts, wheel vehicle loads are considered.
  • Ice Pressure: This is another force that can act on gravity dams.

• Dynamic Forces

  • Earthquake Pressure/Forces: Seismic static loading due to self-weight and other loadings is applied in the analysis of structures like aqueducts. Earthquake pressure is also a force acting on gravity dams.

Additionally, while not a direct force acting on the structure, the potential for erosion and scouring caused by water flow is a critical consideration in the design of cross drainage works, as it can lead to functional or structural failures. These structures are also designed to prevent flooding and waterlogging.