SUBSURFACE INSTRUMENTATION

Monitoring of earth movement and groundwater conditions is a necessary part of many forensic and insurance claim investigations and is intrinsic to the investigation of landslides. DHLA’s personnel have been installing monitoring instrumentation for over thirty years. We have worked closely with nationwide monitoring equipment manufacturers to help develop practical, easy to install and accurate monitoring equipment. There are many different types of instrumentation used for a variety of applications. DHLA designs instrumentation systems that will allow us to build data bases on the subsurface characteristics of a variety of sites. This data can allow us to make construction or repair recommendations tailored to site-specific conditions.

Groundwater can impact the design of foundations and can greatly influence the stability of a site. Currently in Southern California, there is a growing concern with water intrusion and the resulting mold problems. Determination of groundwater conditions is requisite to the design of repairs for moisture intrusion. DHLA routinely installs open standpipe piezometers and pore pressure transducers to monitor groundwater.

Where distress is due to a landslide movement, the first priority is to determine the limits, depth and rate of movement of the moving soil mass. This is accomplished by installing slope inclinometers. Our staff has installed slope inclinometers to depths approaching five hundred feet. DHLA personnel have extensive experience installing and monitoring slope indicators. The grout backfill for inclinometers and pore pressures transducers is formulated to match the surrounding soil strength and permeability. Monitoring of the slope indicators is performed by DHLA and the collected data is reduced and analyzed at our office. The results are presented to the client in letter report format.

DHLA also installs and monitors load cells, strain gauges and settlement monuments for post-construction monitoring. As with other forms of instrumentation, all data is collected, reduced and analyzed by experienced DHLA personnel.

No matter what the site specific subsurface conditions are, a properly designed and executed instrumentation program when combined with a well organized subsurface exploration plan will yield the greatest benefit for the client.

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