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Geotechnical Terminology

The terminology below is designed to allow you to better explain the issues you may be having and bette understand the terminology the may be used during our discussions.

Auger
A cork screw like drill tool designed to remove the soil from a drill hole without using air or water. This method does not require vibration or impact to create the drill hole.
 
Bentonite
A Clay material that is mined in the mid-west and typically ground into a powder. Bentonite is normally used in test drilling to prevent the drill hole from caving. It is also used in cosmetics and even some candy bars.
 
Compaction Grouting
The typical method of grouting used to stabilize cover subsidence sinkholes. The primary difference between this technique and pressure grouting is that the grout material for compaction grouting is a thick, mortar-like material that is designed to displace soft soils and fill voids.
 
Cover Collapse Sinkhole
The most graphic of sinkhole conditions. These conditions result when the "roof" of a limestone dome will no longer support the weight of the soil and or what is located above the surface of the ground. The most rare sinkhole condition.
 
Cover Subsidence Sinkhole
The most common type of sinkhole condition. Unlike the cover collapse sinkhole, this type sinkhole typically moves slowly over a period of time. A passageway in the limestone allows soil particles to flow into a larger void or opening similar to the way sand from an hourglass passes from the top to the bottom. Like the hourglass, a depression or subsidence occurs at the surface when enough sand or soil moves into the deeper void.
 
Cone Penetration Test
This test uses a metal rod or tube fitted with a special point that is equipped with sensors that measure the resistance that is required to advance the point through the soil as it is hydraulically forced into the ground.
 
Foundation
The structural system constructed below a building which transfers the weight of the building to the ground on which it stands.
 
Geotechnical
Dealing with soils beneath the surface of the ground.
 
Geotechnical Report
A compilation of test data and opinions prepared by a specialty engineering company or geotechnical engineer. This report will typically contain the results of soil borings (SPT borings), ground penetrating radar analysis and other specific tests related to the site specific soil conditions.
 
Grout
A cement based material similar to the mortar that is used to lay bricks. A specially designed mixture that utilizes portland cement, fine sand, fly ash and water. Small diameter stone may also be added to the mixture depending on the particular project. This material is typically delivered to the site by local concrete suppliers on residential stabilization projects.
 
Grout Injection Point
A hole drilled for the purpose of injecting grout material. For most sinkhole stabilization projects, this hole is drilled to the top of competent or firm limestone. This depth can vary dramatically depending on local conditions. The hole can initially be advanced with continuous flight augers or installed by spinning a steel pipe into the ground while using a drilling fluid. In either case it is important that a steel flush joint casing be installed the entire depth of the hole. The casing will ultimately be used to inject the grout material.
 
Grout Take
The volume of grout material that is required to treat a particular zone or project. Grout takes are typically estimated during the proposal phase of a project, however, the actual amount of grout required will only be determined after the project is completed.
 
Heave
The upward movement of the ground. This can be a result of several conditions. For the purpose of residential soil stabilization, typical causes would be:
 
Karst
A geologic term that refers to an area where limestone lies beneath the surface. Karst Geology is where soils are underlain by limestone material, which is partially dissolved by groundwater. The resulting voids in the rock provide paths through which water can travel, eroding soil with it.
 
Limestone
The bedrock layer that typically lies beneath central Florida. This rock layer also contains the two major aquifers in Florida; The Floridian which extends across the entire state, and the Biscayne which is found only in South Florida. The Floridian aquifer is a confined Artesian aquifer. The upper part of the Floridian is used as a water supply in north and central Florida. The lower part is mostly found to be salty in coastal areas.
 
Settlement
 The downward movement of the ground surface of a structure or element situated on the surface.
 
Sinkhole
A subsurface condition resulting from the softening or dissolving of limestone over geologic time. Definition.. "a depression caused by the soil and other materials subsiding into an open hole or void below the ground surface" Typically classified as either Cover Collapse or Cover Subsidence Sinkholes.
 
Standard Penetration Test
Used to determine the density of subsurface soils. This test documents the number of "blows" required to advance a steel test spoon one-foot by dropping a 140 pound hammer thirty inches. The recorded number of blows is referred to as an " N Value"
 
Steel Piering
A process by which the weight or load of a structure is transferred through a problematic soil condition to a suitable bearing strata such as rock. In regards to Residential Steel Piering, this usually involves the installation of small diameter (usually three inch) steel pipe sections directly adjacent to the foundation. The pipe sections are typically hydraulically jacked or drilled down to the bearing zone. A foundation attachment or bracket is then mounted to the top of the mini pile and situated to transfer the weight of the foundation section to the mini pile. The mini piles are typically spaced from 4 - 8 feet on center across the affected area depending on structure loads. Steel Piering systems should be designed by a Professional Engineer.
 
Target Quantity
This is the pre-determined quantity of grout material that is placed in a particular zone or injection point.
 
Water Table
The distance below the ground surface at which the soil is completely saturated with water.