What Does Soil Heaving Mean?
Soil heaving is the tendency of the soil over the borehole to rise upward due to soil pressure from the drilling or ramming operation. Heaving can be dangerous if there are utilities in the surrounding soil or structures on the ground above the borehole. To prevent soil heaving and damage to buried structures and utility conduits, a thorough soil investigation should be carried out.
Soil heaving usually occurs when the depth of borehole excavation is shallow. Trenchless technology utilizes pipeline installation methods such as pipe ramming and microtunneling that dig below the ground surface in order to minimize disturbance to surface traffic.
Trenchlesspedia Explains Soil Heaving
Soil heaving can be contributed by different factors such as borehole pressure, excavated depth, flow of drilling fluid, rate of back reaming, moisture content of soil and grout pressure. During the drilling process, the pressure in the borehole may increase due to excess pressure and flow of drilling fluid.
This builds up pressure in the pores of the soil resulting in soil heave especially in soft ground. Negligible heave is acceptable but should not exceed 0.5 inches. Directional drilling has increased in popularity due to its ability to cross through busy locations but incidences of heaving have raised concerns for damage to foundations and pavements.
Well planned drill paths, professional and thorough geotechnical investigation combined with a skilled operator can eliminate the problem of soil heaving during trenchless operations.