when a Bunsen burner is lit below a wire gauze, the flame initially burns below the gauze, after some time it burns both below and above. Explain this observation​

Use the profile illustrated for problem (1). assume that the layer of silty sand fill (sm) is placed over the entire site. estimate the thickness of the fill (h - in feet) that will cause the effective vertical stress at the center of the clay layer to increase by 517.5 pounds per square foot.