Change Columns Settlement For Free

As a first approximation, a general value of the critical column length of 2 and 2.5 times the footing diameter may be considered for ordinary and encased stone columns, respectively.

Stone columns are probably the most "natural" ground treatment method or foundation system in existence to date. The benefit of stone columns is owing to the partial replacement of compressible soil by more competent materials such as stone aggregate, sand and other granular materials.

An optimum area replacement ratio of 30?40% exists for the control of settlement. The settlement performance of a small column group is highly influenced by inter-column and footing interaction effects.

Stone column ground improvement involves adding vertical columns of stone into the ground to a depth of at least 4m below the ground surface. A layer of compacted gravel can then be put over the top of the columns, ready for the construction of new house foundations.

When the columns are installed, the area replacement ratio is defined as the ratio of the cross-sectional area of a column to the tributary area of the column, as shown in Figure 1. Under rigid loading, the stress distribution on the columns and the soil can be simplified as shown in Figure 2.

An optimum area replacement ratio of 30?40% exists for the control of settlement. The settlement performance of a small column group is highly influenced by inter-column and footing interaction effects.

Consequently, the frame of the building may become distorted, floors may slope, walls and glass may crack, and doors and windows may not work properly. Uneven foundation settlement may force buildings to shift out of plumb which lead to crack initiation in foundation, structure, or finish.

WHY DO FOUNDATIONS SETTLE?Drought.Maturing Trees.Poor Drainage.Busted Pipes & Leaking Water Lines.Poorly Compacted Soil.Weak Bearing Soil.Moisture Content Changes.Soil Consolidation.

How much foundation settlement is too much? The industry standard is 1 inch of differential settlement in 20 feet. Anything greater than this can be considered too much.

In such circumstances, it becomes essential to improve the foundation soil to address permissible settlements by means of the following:Compacting the soil.Draining the soil, in case of cohesive types.Compacting the soil, in case of cohesion less soils.Confining the soil, increasing stiffness.Grouting.