Soil inclusions (30) comprising an elongated, cured cementitious columnar body (72) are located within the soil (32) and include a tubular perforate structural reinforcement (56a, 56b) embedded within the body (72), with portions of the body exuded through the perforations (57) of the structural reinforcement (56a, 56b). The inclusions (30) are formed by driving a tubular mandrel (44) through vibratory means into the soil (32), with a flexible, tubular, perforate reinforcement (56a, 56b) about the exterior surface of the mandrel (44). When the mandrel (44) is fully driven, it is withdrawn, and simultaneously cementitious material (70) is injected into the mandrel (44). The material (70) exudes through the perforations (57) to complete the inclusion (30), which is deformation compliant. The inclusions may be installed in vertical or non-vertical orientations.