Frequently Asked Questions
The soil is composed by particles (minerals and sometimes organic material) and voids (pores) between these particles. These voids usually contain air or water. The general principle of grouting is to fill or reducing the voids with a different material (usually a cementitious grout or a chemical grout) therefore improving the mechanical properties of the soil and reducing its permeability.
Cohesive soils like clays have limited voids and are less prone to grouting techniques. Granular soils like sands and gravels have large volumes of voids and are more compatible with grouting techniques.
These techniques may be summarized in:
- Permeation grouting;
- Compaction grouting;
- Intrusion grouting;
- Jet grouting;
- Rock grouting.
Please note that each of these categories have several different methods of installation.
Consist in filling the soil pores with grout without disturbing the soil formation. The grout permeates through the soil particles filling the voids occupied by the air or water, ideally without moving the soil particles. The installation is conducted by low pressure injection of low viscosity grout. The grout viscosity is selected based on the permeability of the soil.
This technique is used for:
- Control ground water flow, especially during excavation;
- Increasing the stand-up time of soils when excavated;
- Increase the strength of soils
- Control settlements
This technique is versatile and therefore often used when site access or presence of utility encroachments are a challenge. On the other hand, the grout can travel though the soil only for relatively limited distances, depending on the soil permeability.
Rockfall (or rock fall) is an engineering science belonging to rock mechanic principles. As first step we identify what is the application, whether it is an existing rock rim, a slope or a rock cut, rock excavation. Then we do a rock mass characterization, identifying the rock mass properties, localizing which blocks are considered unstable, the detachment zone of these blocks and the type of initial movement those blocks may have. Once detached the blocks gain energy proportionally to their mass and velocity during the fall, but they also lose energy due to impacts along the trajectory, air friction and type of motion (for instance a rolling motion along a slope will dissipate more energy compared to a free vertical fall from a rock rim). We analyze all the above with kinematics and dynamics principles and statistical approach.
Once we are comfortable with our analyses and we determine the block trajectory, we consider one of the following solutions or the combination of several of them:
- Rockfall trenching;
- Rockfall embankments;
- Rockfall barriers;
- Debris flow barriers;
- Rockfall attenuators;
- Simple draperies;
- Pinned draperies;
- Rock bolting;
- Rock scaling.
When we design-build a range we use solutions that limits the width of rear backstop and sidewalls. Preparing properly the foundations and using reinforced soil techniques, prefabricated cages or pile walls systems, we can reach the backstop minimum required height of 20 ft by using a base of only 15 ft or less, rather than having a base of 40 ft to 50 ft that a regular dirt berm would need for such height. This increase the square feet available to accommodate the actual training ground. Our solutions also require less maintenance, for instance the typical washout that standard dirt berm experience after heavy rains.