A recent housing development off Hessle Road required a deep cut into the local glacial till. The contractor noticed tension cracks forming along the upper bench after a week of heavy rain. That is exactly when a proper slope failure analysis becomes critical. Without it, the entire site could have experienced a progressive collapse. We investigated the stratigraphy, performed a geotechnical study to confirm the soil parameters, and used limit equilibrium methods to determine the factor of safety. The analysis showed that the slope was stable under dry conditions but dropped below 1.3 when fully saturated. That finding changed the design approach entirely.
A saturated clay slope in Hull can lose over 40 percent of its undrained shear strength within 48 hours of heavy rainfall.