Papers by Vincent Drnevich
The Purdue TDR method is a new technology for simultaneously measuring soil water content and dry... more The Purdue TDR method is a new technology for simultaneously measuring soil water content and dry density insitu. An ASTM standard for using TDR to measure soil water content and dry density based on Purdue TDR method was approved during the time span of this project and is designated ASTM D6780. The primary objective of this study was to take the Purdue TDR Method to the point where it is widely field tested by users on a broad spectrum of soils around the country. This goal was achieved by involving researchers at other universities and practitioners in federal and state agencies and in private practice firms. The results and feedback was obtained from Beta Partners by Purdue University for evaluation and further analysis. Major achievements in this research include: 1) Involvement of Beta Partners -Six Beta partners including two universities, two private firms and two state DOTs were involved in this project and instructions were provided to each Beta Partners. Involving these Beta partners provided a large span of field applications and research feedback. Results from testing performed were compared with existing technologies and provided the basis for the precision and bias statements needed for ASTM D6780. Based on feedback from extensive field tests, testing procedures were improved. Meanwhile, the testing equipment was refined and integrated, which made the testing system both more robust and easier to handle. The overall cost of the testing system has also been significantly reduced, which made it more economically competitive for mass production. 2) Testing automation -A new generation of electronics was identified and incorporated into the Purdue TDR test, the new TDR100 by Campbell Scientific, Inc. Corresponding software for automation was designed and systematically improved. This provided a user friendly interface and facilitated performance of TDR testing process. Preliminary feedback from using the computer software is satisfactory. The efforts and achievements on testing automation also built up the basis for a developing a more compact package in the future. 3) One step method for TDR testing -A simplified procedure to that described by ASTM D6780 to measure soil water content and dry density was discovered, which is an important product of this project. The simplified procedure is called the one-step method since it only requires one field TDR reading. The one-step method achieved this simplification by incorporating information of bulk electrical conductivity from TDR signal in addition to the apparent dielectric constant used by previous TDR test. A scheme to account for the difference between field conditions and laboratory situations was developed, which serves as the basis of the one step method. A simplified temperature compensation scheme was also designed which makes it possible for the one-step method to deal with complex field situations. Computer software was developed to automate the performance of one-step method in the field. TDR for non-conventional materials -The discoveries in developing the one step method as well as the advancement in software development significantly expanded the application domain of the TDR system. More potential new applications for TDR technology in civil engineering practice were identified. One of these is the application of TDR to non-conventional materials such as fly ash, lime stabilized soil and Portland cement concrete. The range of applications for the TDR technology developed in this research is ever broadening and will have significant impact in the future on the testing of civil engineering materials.
Journal of Geotechnical and Geoenvironmental Engineering, 2007
This paper presents a model-based approach to determine dielectric constants from time domain ref... more This paper presents a model-based approach to determine dielectric constants from time domain reflectometry ͑TDR͒ measurement in highly conductive soils. It makes use of information contained in the TDR signal from the reflection at the surface of the soil rather than the reflection from the end of the probe. The TDR method is widely used to determine the volumetric water content of soils. Commonly used information from the TDR signals includes the apparent dielectric constant and the electrical conductivity. The apparent dielectric constant is generally measured by analyzing the travel time of electromagnetic waves reflected from the end of the soil probe. In soils with high electrical conductivities, the attenuation of the signal can eliminate the reflection from the end of the probe, which limits the application of TDR to these materials. A simplified frequency-independent dielectric model is utilized to invert the dielectric constant from the reflected signals at the soil surface. Results indicate that the dielectric constant can be determined with reasonable accuracy by the proposed approach for soils with high electrical conductivity, where the conventional travel time analysis fails due to significant signal attenuation.
Lime and Lime Kiln Dust (LKD) are widely used for modifying/stabilizing pavement subgrades. The a... more Lime and Lime Kiln Dust (LKD) are widely used for modifying/stabilizing pavement subgrades. The addition of lime or LKD involves chemical processes that are dependent on many parameters. For natural subgrades, quality control is based on moisture and unit weight requirements using manual interpolations of one-point test data on a family of curves. For modified soils, moisture and unit weight measurements are insufficient for quality control and other tests must be considered. Various possible quality control methods for LKD-modified subgrades were evaluated. This research produced an Excel-based program to automate the generation of a family of curves and one-point data interpolation. Families of curves for LKD-modified soils did not vary systematically, limiting their usefulness in quality control. Dynamic cone penetrometer (DCP) and Time domain reflectometry (TDR) tests were considered as alternative means to achieve field quality control. The DCP test although promising, requires supplementary tests for completely characterizing a modified subgrade. LKD modification of soil involves chemical reactions which can be indirectly studied by measuring the electrical properties. The dielectric constant and electrical conductivity of a LKD-modified soil were measured using the Purdue TDR apparatus. Preliminary test results show that with the knowledge of two calibration constants, the dielectric constant of a soil measured following the Two-Step TDR test (ASTM D 6780) can be used for water content and unit weight determinations. The electrical conductivity of a LKD-modified soil decreases with time in a manner that is similar to the one-dimensional consolidation of a soil. The variation in electrical conductivity with time of a LKD-modified project soil was correlated to its strength and was also used to estimate the amount of LKD present in the soil. Future research should focus on extending these observations to other soils and to formulating a protocol for using the TDR test along with the DCP test for quality control of LKD-modified soils. .
The methodology developed by Siddiqui and Drnevich (1995) for measuring soil water content and de... more The methodology developed by Siddiqui and Drnevich (1995) for measuring soil water content and density using Time Domain Reflectometry (TDR) was extended for routine use in the quality control testing of compacted soils. The objectives of the study were to develop computer software to automate data interpretation and data reduction, develop prototype equipment for field use, compare the results of the TDR method with the sand cone and nuclear density methods on actual construction sites and develop draft specifications for ASTM and AASHTO. New prototype equipment was developed for compaction quality control testing. Waveform interpretation and data reduction were automated by incorporating developed algorithms into a Windows based computer program that is used on a palm top computer connected to the TDR apparatus. Over 150 laboratory and field tests were performed to evaluate the TDR equipment and procedure for use in the determination of moisture content and density of compacted soil.Under field conditions it was shown that the TDR method is more accurate than the nuclear density gage in estimating water content when compared to oven drying, with standard errors of 1.1% and 1.8%, respectively. The ability to assess the accuracy of the TDR method for determining density was limited because the true density of the compacted soil is not known. The sand cone test was used as a basis for comparing the TDR and nuclear density tests on several sites while accepting that the sand cone test is not an exact method. The time required to perform the TDR test under field conditions is approximately 1 5 to 20 minutes. The sand cone test can also be performed in approximately 1 5 minutes, while the nuclear density test can be performed in approximately two minutes. The time required to complete the TDR test relative to the nuclear density test, is viewed as its greatest limitation. In general, the nuclear gage provides estimates of density and water content much more rapidly than the sand cone or TDR tests, is less accurate than the TDR test in estimating water content, and must be calibrated for a specific soil using sand cone tests. Moreover, the nuclear gage uses a hazardous source requiring operators to take safety training and leading to expenses associated with equipment maintenance and disposal. The sand cone test is time consuming, and can not provide estimates of water content. The TDR test is also time consuming, but does provide accurate estimates of water content. At the present stage of the research, the TDR test has not shown great advantage in the measurement of water content and density relative to the nuclear density test. However, progress is being made in the development of an approach to use other features of the reflected waveform, in addition to the apparent dielectric constant, within the interpretation process. It is anticipated that the additional information that can be obtained from the reflected waveform will allow a more accurate estimate of density to be obtained while eliminating the need to recompact the soil in a mold. This should greatly reduce the test duration. 17. Keywords Soils, water content, density, field compaction control, time domain reflectometry, dielectric constant, coaxial transmission lines, multiple rod probes, data automation.
The contents of this report reflect the views of the authors who are responsible for the facts an... more The contents of this report reflect the views of the authors who are responsible for the facts and the accuracy of the data presented herein. The contents do not necessarilY reflect the official views or policies of the
2008 Annual Conference & Exposition Proceedings
This paper presents a basic trend study conducted at a large university in the midwestern United ... more This paper presents a basic trend study conducted at a large university in the midwestern United States. The results of the study suggest a progressive decline in the understanding of a particular component of ethical judgment among the civil engineering students at the academic institution where the study was conducted. The study included twenty separate assessments administered to engineering students between 1991 and 2008. This paper contains a detailed discussion of the assessment tool, administration procedures, and analysis of results. The component of professional ethics, as presented by the assessment tool, will be evaluated in relation to ABET EC 2000, and assessment items will be evaluated relative to the engineering codes endorsed by IEEE, ASCE, and NSPE. Finally, data trends will be evaluated relative to their implications with respect to the role of the engineering profession in society.
Advances in Pavement Engineering, 2005
... Earth Sciences and Research Laboratory, Technical Service Center, Bureau of Reclamation,Denve... more ... Earth Sciences and Research Laboratory, Technical Service Center, Bureau of Reclamation,Denver, CO. [21] USBR 5535-94, DRAFT. Procedure for Determining the Maximum Index Unit Weight of Cohesionless Soils using a Vibratory Hammer. Unpublished manuscript. ...
Consolidation of Soils: Testing and Evaluation
Vincent P. Drnevich1 Report on Laboratory Tests for Consolidation Behavior REFERENCE: Drnevich, V... more Vincent P. Drnevich1 Report on Laboratory Tests for Consolidation Behavior REFERENCE: Drnevich, VP," Report on Laboratory Tests for Consolidation Be ... Juarez-Badillo shows that for X= 0 (constant c but permeability and compressibility variable), his solution is identical to ...
This note describes a technique for cutting undisturbed brittle block samples into smaller specim... more This note describes a technique for cutting undisturbed brittle block samples into smaller specimens for further geotechnical testing. This technique revealed very useful in dealing with collapsible soils, where the sampling is recommended to be done with block soil samples. A further use of this technique as an efficient way for sampling collapsible soils is proposed.
Although it is known that impact compaction tests are not appropriate for granular soils, these t... more Although it is known that impact compaction tests are not appropriate for granular soils, these tests continue to be widely used. Excessive settlements frequently occur in granular soils where specified field compaction is based on Standard Proctor (ASTM D 698; AASHTO T 99) maximum dry unit weights. A laboratory test program evaluated alternative test methods for granular soil compaction control and showed that a Vibrating Hammer method (similar to British Standard BS 1377:1975, Test 14) has great promise for laboratory compaction of these soils. A One-Point Vibrating Hammer test on an oven-dry soil sample is able to provide the maximum dry unit weight and water content range for effective field compaction of most granular soils. The maximum dry unit weight obtained is comparable to that from other current methods such as the Vibrating Table test (ASTM D 4253) and the Modified Proctor test (ASTM D 1557), and is greater than that from the Standard Proctor test (ASTM D 698). The method is applicable to a broader range of soils than current vibratory table compaction tests (up to 35 percent non-plastic fines and up to 15 percent plastic fines). The equipment is relatively inexpensive and is portable enough to be taken into the field. The test is easier and quicker to perform than the other methods mentioned above and provides reproducible and consistent results. Large sized granular soils/aggregates create potential problems for compaction control methods due to the presence of oversize particles. Oversize particles defined here are those retained on a 3/4-inch (19-mm) sieve. INDOT Specification 202.34 (b) 2 requiring correction of densities from laboratory compaction tests on soils with oversized particles is not being used in practice. It is not being followed primarily because guidance is not provided. As a result, the values of maximum dry unit weight from standard compaction tests will be significantly lower than those corrected for oversized particles. This finding may be the biggest reason why granular fills with oversized particles are under-performing. The proposed Vibrating Hammer Method of Compaction specifically addresses the influence of oversize particles. Based on the results from this research, a draft ASTM Standard for the Vibrating Hammer Method of Compaction has been written, is well into the balloting process, and should become an ASTM Standard Method of Test in late 2007 or early 2008. It is included in Appendix A. This report also introduces a simple calibration procedure to verify that the vibrating hammer is supplying sufficient energy to the soil. The Vibrating Hammer Method of Compaction is an alternative method for specifying maximum dry unit weights for granular soils. The method also establishes a water content range for field compaction. This research expands the applicable range of granular soils to those containing oversize particles. An experimental program, along with review of previous compaction research, was carried out to determine the effect of oversize particles on compaction performance. Testing was performed in two sizes of compaction molds, 6inch and 11-inch, in determining this effect. An oversize correction method was considered for water content and dry density when performing a test in a 6-inch mold with scalping, i.e. removal of oversize particles. Results of an INDOT pilot implementation project used to determine the viability of using the Vibrating Hammer for field compaction are reported. Results indicate that the Vibrating Hammer method is sufficient for use with oversize particles and that maximum dry unit weights may occur at or near saturation.
Geotechnical Testing Journal, 2014
For more than 50 years, the resonant column test has been used to measure the shear modulus and d... more For more than 50 years, the resonant column test has been used to measure the shear modulus and damping of soils for shear strains ranging from 10−5 % to 0.5 %. For most soils, the test is non-destructive, and tests may be performed on the same specimen at multiple confining stresses simulating in situ conditions from near surface to great depths. This paper makes use of the transfer function approach for resonant column theory to obtain simple solutions for the test and applies it for two types of resonant column apparatus: the conventional fixed-base free top (including spring top) now referred to as device type 1, and for a new type of resonant column device, device type 2, where a torque transducer is mounted in the bottom platen of the device. Device type 2 uses the torque measured at the base of the specimen and the rotation measured at the top of the specimen to determine the shear modulus and damping. The advantage for taking torque measurements at the base of the specimen is because the torque that is measured is that transmitted by the specimen alone. Calibrations of top platen inertia, stiffness, damping, and torque input are not needed for device type 2. Solution of these equations with complex variables can be done with any number of programming languages. For example, simple, single page, Excel spreadsheets for each device type are provided. The paper concludes with a discussion of issues that need to be addressed before procedures involving non-resonant frequencies can be introduced into ASTM D4015 [ASTM D4015: Standard Test Method for Modulus and Damping of Soils by Fixed-Base Resonant-Column Method, Annual Book of ASTM Standards, ASTM International, West Conshohocken, PA, 2007].
Journal of Professional Issues in Engineering Education and Practice, 2012
The civil engineering capstone senior design course at Purdue University involves all seniors in ... more The civil engineering capstone senior design course at Purdue University involves all seniors in their last semester before graduation and is titled "Civil Engineering Design Project." The course catalog describes it as "Planning, design, and analysis of a civil project; an integrated and realistic group project involving as much as possible all major aspects of the civil engineering profession." This highenrollment course (30-120 students per semester) has been team taught since the early 1960s and many approaches to teaching it have been utilized. Since 2001, the version of the course discussed in this paper has been taught in the spring semester with the student teams responding to a request for proposals (RFP) for local projects following the design-build method of project delivery. The proposals are submitted in two phases: (1) conceptual designs and alternatives analyses; and (2) design-build project proposal with approximately 30% complete design, total construction cost, and scheduling. The design-build proposal is the culminating activity in the course. Both phases have oral presentation components. Students are assigned to teams on the basis of factors that include overall grade point average, grades in key courses, work experience, computer software skills, and Meyers-Briggs typology. Peer evaluations, time sheets, and invoices for services are required. Since 2007, projects have had to meet LEED requirements specified by the U.S. Green Building Council. Continual development of the Purdue University civil engineering capstone course is anticipated to serve as a case study for other civil engineering programs looking to develop or revise their senior design course.
Geotechnical Testing Journal, 2013
ABSTRACT
Geotechnical Testing Journal, 1985
Methods of time series analysis based on the Box-Jenkins method were used to analyze random varia... more Methods of time series analysis based on the Box-Jenkins method were used to analyze random variations and inherent variability in geotechnical test data. The paper presents a summary of the time series models and their application to the analysis of data from unconfined compression tests, field vane tests, and cone penetration tests. The integrated-moving-average-autoregressive model was found to be a versatile tool and served this purpose well. The model permits the determination of the autocavariance function and the random testing error that best fit the test data.
Geotechnical Testing Journal, 2013
This paper describes a new type of torsional resonant column device that has a quasi-fixed base a... more This paper describes a new type of torsional resonant column device that has a quasi-fixed base and free top. In this device, a relatively rigid torque transducer is placed between the bottom platen and the fixed chamber base. A large capacity torque motor excites the top platen. The primary measurements during the test are the rotation of the top platen, the torque at the specimen base and excitation frequency. An equilibrium equation for the bottom platen relates the torque transducer output to the torque applied by the specimen to the bottom platen. Using equivalent linear viscoelastic theory, a stiffness matrix is generated that relates the torque and rotation at each end of the specimen to specimen properties. A hybrid magnification factor is d+efined as the ratio of motion at the top of the specimen to that at the base. These two measurements provide the data needed to determine the shear modulus and damping ratio in the specimen for each frequency. The benefit of this approach is that the modulus and damping ratio of the soil are determined independent of the torque applied by the torque motor to the top platen. This removes the problems of torque motor characteristics, bearing friction, back EMF, and eddy current damping that occur with torque motors, which in turn allow more precise and repeatable determination of shear modulus and damping ratio over a wide range of shear strain and frequency. The paper outlines the theory, describes the apparatus and calibration procedures, and provides sample test data.
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Papers by Vincent Drnevich