Advanced Construction Techniques Ltd. (ACT) services

ACT has devised an innovative approach to view subgrade conditions with its IntelliCam system, offering a wide array of applications to the underground civil and geotechnical industry. This system allows for first hand inspection of in-situ rock conditions. ACT can offer our clients a better perspective of in-situ conditions, which allows for a streamlined problem solving strategy.

ACT offers a broad scope of geotechnical instrumentation installation services. Piezometers, inclinometers and extensometers, to name a few, are commonly used to monitor site conditions. We also offer monitoring systems capable of detecting movement in structures and monuments including crack gauges, liquid level sensors, or robotic survey.

ACT owns several rotary duplex drill rigs capable of using either auger rotary or eccentric drill tooling systems for overburden drilling. Typically, this type of drilling is used for rock anchors, soil nails, micropiles, overburden casing installation or holes of large diameter or long-reach drill holes. ACT`s rotary duplex drills utilize inner and outer drilling strings housed in a magazine rack. The magazine rack, operated by hydraulics, allows the drill string to be loaded and unloaded. The drill head is equipped with a twin-impact system that permits rotary percussive drilling with both the inner drill rod and outer drill casing simultaneously, thus reducing drilling time.

Jet Grouting creates in-situ columns of grouted soil using very high pressure grout injection. Grouting is performed by pumping high velocity jets of grout (or sometimes grout and air or grout, water and air) through the side of a grout monitor, attached at the end of the drill string. The jets erode and mix the soil as the drill string and the monitor are being rotated and withdrawn.

Vibro Columns, which can be either stone or concrete, are designed to transfer building loads through a weak layer of soil to an underlying competent layer. A bottom-feed dowhhole vibratory probe is advanced through the weak soil layer, such as organic soils, to the underlying firm layers. Granular bearing soils are densified by the vibrator. In Vibro Concrete Columns (VCC), concrete can either be pumped through a tremie tube attached to the vibratory probe or the materials can be dry-mixed at the surface and then be bottom-fed by the tremie tubes. In Vibro Stone Columns (VSC), crushed aggregate is used instead of concrete to provide the means of load transfer. In both techniques, a pile cap can be constructed, joining the grid of columns to provide support for foundations.

Rock and Soil Anchors are structural members that are used to provide temporary or permanent structural support.  A rock or soil anchor consists of a tendon and an anchorage. The tendon can be one or more solid steel bars, a single hollow bar, or a bundle of high strength tensile steel strands. After drilling, installation and grouting, the anchors are tested to ensure that they are capable of carrying the design loads. Both performance and proof tests are performed in accordance with PTI prior to locking the anchors off at the required load. In some instances, anchors are installed but not stressed and remain passive.

Soil Nails are steel reinforcing members that are typically installed in a closely spaced grid pattern, fully grouted, passive (non-tensioned) anchors that when covered with shotcrete, create a cohesive mass with improved shear strength to prevent slope failure. Soil nails are generally used where prestressing is either not possible or desired. They are advantageous when the slope being treated is vegetated with mature growth that can, by conscientious design and installation considerations, be preserved intact. Soil Nail Walls are constructed in stages/lifts using the top down method. Stages are excavated, followed by installation of the soil nails and shotcrete to support the stage. Successive stages are created by repeating this process until the desired bottom elevation is reached.

Compaction grouting is typically performed in loose or weak soils to mitigate settlements and is also used for sinkhole remediation. Compaction grouting involves the injection of a very stiff, mortar like, cementitious grout into soil to densify or compact the soil under high pressure. When injected, the grout will not permeate the surrounding soils, but instead form “grout bulbs” that laterally displace the soil. By repeating the process in adjacent holes the soil between the holes is densified through the lateral displacement.