TECHNICAL RESOURCES

Field Equipment & Instrumentation

DHLA is well equipped to handle a variety of functions in the field.  Our sampling equipment is capable of collecting relatively undisturbed soil samples in a variety of subsurface conditions, from sensitive, very soft and saturated soils, to very hard soil or soft bedrock. Specialized field locating tools allow for accurate documentation and mapping of site geologic conditions.  For the purpose of observing subsurface conditions, our personnel use only OSHA-approved equipment to safely enter boreholes and excavations.

DHLA possesses state-of-the-art instrumentation for the monitoring of groundwater and earth movement, including slope inclinometer and tiltmeter systems that are computer-interfaced for rapid data collection in the field, and data processing and analysis in the office.  Our water level devices are capable of determining foundation deflections to within a tenth of an inch for foundation distress evaluations. Nuclear gauge instrumentation for field compaction testing is maintained in accordance with State and Federal regulations, under the supervision of a licensed radiation safety officer. Strong emphasis is placed on maintaining the best equipment and instruments in order to ensure the most efficient and accurate data collection possible.

Soil Laboratory

DHLA takes pride in our soil laboratory, which is outfitted with state-of-the-art equipment and managed by highly trained, qualified technicians. Our laboratory has, in fact, been contracted by many other consulting engineering firms and engineering contractors. Much of our testing equipment is automated to include test control and data acquisition by computers.  Our laboratory conforms strictly to ASTM, AASHTO, and CalTrans standards, and receives annual quality assurance calibration.

Our in-house and outsourced geotechnical laboratories are currently certified as approved soil testing agencies with the City of Los Angeles.  A partial list of the soil and rock testing capabilities we can provide includes: 

Moisture & Density

Expansion Index

Specific Gravity

Swell Tests

Grain Size Distribution

Consolidation Tests

Phi Grain Size

Direct & Residual Shear

Atterberg Limits

Triaxial Tests (outsourced)

Maximum Density Tests

R-Value Tests (outsourced)

Sand Equivalent

Chemical Tests (outsourced)

Computer Support

DHLA relies heavily on computer support for instrumentation monitoring, engineering analysis, laboratory testing, and office applications.  Our entire computer network has high-speed internet access, e-mail, and various state-of-the art programs.  An additional notebook computer is interfaced to our slope inclinometer and tiltmeter equipment for rapid data collection in the field.

A partial list of our specialty engineering programs includes: 

AutoCAD LT 2005 – Computer-aided drafting program for full-size color maps and engineering drawings.

GSTABL – In-depth analysis program, with Windows-based editing software, for slope stability applications.

EQFAULT – Database and analysis program for the deterministic prediction of peak horizontal acceleration from digitized California faults.

ISIS – Computer-driven interface system for rapid recording and processing of slope inclinometer and tiltmeter data.

EQSEARCH – Database and analysis program for the estimation of peak horizontal acceleration from California historical earthquake catalogs.

LIQUEFY2 – Analysis program for the empirical prediction of earthquake-induced liquefaction potential.

FEADAM – Finite element program for analysis of embankments and earth dams.

LPILE – Analysis program for design of laterally loaded piles.

FRISKSP – Database and analysis program for the probabilistic estimation of seismic hazards using faults as earthquake sources.

SURFER – Graphics program for contouring and 3-D surface mapping.

SHAFT – Program for computing the axial capacities of deep foundation elements.

UBCSEIS – Program for the estimation of Uniform Building Code Coefficients using 3-D fault sources.

gINT – Specialized geotechnical database program for managing, integrating and displaying data generated from subsurface geologic and engineering exploration, and laboratory testing.

Geotechnical and Geologic Library 

DHLA maintains an extensive collection of technical books and periodicals, conference proceedings, manuals, building codes, geologic maps, and aerial photos.  Our geotechnical and geologic library is kept up-to-date with recent publications to complement the materials collected by our professionals over the past several decades. Research on the Internet also provides an electronic communication link to a multitude of resources beyond our own library. Our personnel are encouraged to study the materials in our library, and to continue to grow in their technical knowledge through extended learning programs. 

Professional Organizations 

DHLA is an active member of several professional organizations, including:

  • California Geotechnical Engineers Association (CGEA)
  • Building Industry Association (BIA) in Orange County
  • BIA Construction Quality Committee
  • Community Associations Institute (CAI)

Our professionals are individual members of the ...

  • American Society of Civil Engineers (ASCE)
  • National Society of Professional Engineers (NSPE)
  • Forensic Expert Witness Association (FEWA)
  • Association of Drilled Shaft Contractors (ADSC)
  • Association of Engineering Geologists (AEG)
  • Geological Society of America (GSA)
  • Society of Women Engineers (SWE)
  • Construction Specifications Institute (CSI)
  • American Society of Testing Materials (ASTM)
  • Post Tension Institute Slab on Ground Committee (PTI)

.. among others.

© Copyright 2017 David H. Lee & Associates, Inc. | All Rights Reserved | Terms Of Use | Site Credits