Slope stability is the potential of soil covered slopes to withstand and undergo movement. Stability is determined by the balance of shear stress and shear strength. A previously stable slope may be initially affected by preparatory factors, making the slope conditionally unstable. Triggering factors of a slope failure can be climatic events can then make a slope actively unstable, leading to mass movements. Mass movements can be caused by increase in shear stress, such as loading, lateral pressure, and transient forces. Alternatively, shear strength may be decreased by weathering, changes in pore water pressure, and organic material.
Slope stabilization is important in the design of such excavations as open pits, quarries, and foundations, rock-fill dams, slopes of other types of embankments, and reservoirs, where movement may have serious consequences. Investigations into slope stability include measurements of shape, geologic structures, and soil strengths. Stabilization can be achieved through slope reinforcement by constructing structural elements such as jet grout or soil mix columns, conventional piles, drilled shafts, or combinations of these. Raito has extensive slope stabilization experience and can bring that knowledge to bear on your project.
DSM is an in-situ soil mixing technology that mixes existing soil with cementitious materials using mixing shafts consisting of auger cutting heads, discontinuous auger flights, and mixing paddles. The mixing equipment varies from single to eight shaft configurations depending on the purpose of the deep mixing. The soil-cement produced generally has higher strength, less compressibility, and lower permeability than the native soils.
RAS Column is an advanced deep soil mixing method based on mechanical soil mixing technology to produce soil-cement column of 1.4m to 2.5m diameter. The mixing head is equipped with the counter rotation mechanism. This unique mechanism efficiently breaks and mixes in-situ soil with cement-based reagents, producing more homogenous and higher quality soil-cement columns.
SCM (Surface Compact Mixing) is a method to mechanically mix in-situ soil with cement powder or slurry. SCM provides two different mixing equipments, Rotary Blender and Bucket Mixing, to be selected depending on improvement objectives and depth. The unique mixing mechanism provides efficient, cost effective and quality improvement. Larger plant is not necessary. The mixing device can be attached to a local 0.8-1.9m3 excavator.
Jet Grouting is a technique of mixing in-situ soil with the energy of ultra-high pressure jet of slurry. A small-diameter rod drills down to the improvement bottom. Then the rod, while being withdrawn, jets the cement-base slurry and air to produce an improved column. Jet Grouting enables improvement closely contacted to or, in some cases, encompassing existing underground structures without causing damage to them.
The reservoir has a total storage capacity of about 177 million gallons or 543 acre-feet and supplies roughly 60 percent of the City’s water. Deep Soil Mixing (DSM) was used to remediate a potentially weak foundation and thereby improve the seismic stability of an earth embankment dam.
The earth-fill San Pable Dam was built in 1920, creating a drinking water reservoir and recreation area notheast of Berkeley. Fill for the dam foundation was hydraulically placed, which can result in poor performance during seismic shaking. DSM was chosen to mitigate liquefaction in the downstream toe of the dam foundation.