On soil-covered slopes, soil is constantly moving downslope due to gravity. Movement can be barely evident or devastatingly rapid. Slope angle, water, climate, and slope material contribute to the movement. The field of slope stability includes the stability of slopes of earth and rock-fill dams, slopes of other types of embankments, excavated slopes, and natural slopes in soil and soft rock. Slope stability is typically evaluated in a geology or geotechnical engineering study.
Steep slope angles are often desirable to maximize the level land at the top or bottom of the slope. However, the slope stability decreases with increasing slope angle. Water plays a major role in slope failure. Rivers and waves erode the base of slopes and remove support. Water can also increase the driving force by filling previously empty pore spaces and fractures, adding to the total mass. Increased pore water pressure can also decrease resistance by decreasing the shear strength of the slope material. Chemical weathering slowly weakens slope material, reducing its shear strength, thus reducing resisting forces. Where integrity of the embankment is vital or in areas subject to detrimental hydraulic forces, additional embankment protection is often required.
Stabilization can be achieved through slope reinforcement by constructing structural elements through the failure plane. Structural elements could consist of conventional piles or drilled shafts, jet grout or soil mix columns, or reinforced rigid inclusions. In granular soils, soil improvement could be performed to increase slope stability.
Anchor block slope stabilisation is a technique that stabilizes slopes or existing retaining walls using anchored reaction blocks. The block layout pattern is typically in rows across the slope or wall. The finished anchored reaction blocks resist the movement of the retained soil or wall.
Anchors are slope stabilization and support elements that transfer tension loads using high-strength steel bars or steel strand tendons. Micropile Slide Stabilization System (MS³) is a slope stability technique that utilizes an array of micropiles sometimes in combination with anchors. The micropiles act in tension and compression to effectively create an integral, stabilized ground reinforcement system to resist sliding forces in the slope.
Soil nailing is a slope stabilisation or an earth retention technique using grouted tension-resisting steel elements (nails) that can be designed for permanent or temporary support. Soil nails can also be installed in restricted access sites, existing bluffs or retaining wall, and directly beneath existing structures adjacent to excavations. Care should be exercised when applying the system underneath an existing structure since some slope movement occurs before the nails begin resisting the load. Soil nailing has been used for slope remediation and landslide repair, to provide earth retention for excavations for buildings, plants, parking structures, tunnels, deep cuts, and repair existing retaining walls.
Gabions are an earth retention technique in which gravity retaining walls are formed using rectangular, interconnected, stone-filled wire baskets. Gabion walls have been used to construct temporary or permanent retaining walls and where slope protection or erosion control is required such as channel linings.
Hayward Baker utilizes extensive 3D modeling to avoid conflicts on your site between individual soil stabilization elements as well as with adjacent foundations and buried utilities. Hayward Baker has extensive slope stabilisation experience and can bring that knowledge to bear on your project.