Assessment of a virtual laboratory for geotechnical engineering (original) (raw)

Abstract

In the study of engineering science phenomena, there is no substitute for hands-on experience opportunities. However, despite the extent to which laboratories are commonplace in engineering education, many obstacles stand in the way of achieving satisfactory hands-on experience. The cost of laboratories and associated experiments, in terms of time, space, and finances, limits the complexity of experiments that can be performed and limits the extent of any lab test series. At some smaller schools, these costs can result in the elimination of laboratory experiences altogether. Additionally, because many undergraduate students have only a basic level of technical ability, lab experiments must be limited to demonstrations of phenomena that are physically obvious (e.g., that a soil sample will deform under load). Virtual reality environments have been proposed as a partial solution to these obstacles. After the initial software development, the cost of preparing and performing laboratory tests is negligible. Multiple tests can be performed, with variations in loading conditions, material types, and boundary conditions, enabling students to observe the more specific details of material behavior as well as general deformation behavior. In addition to serving as an augmented laboratory experience, the virtual environment has potential both as a lecture tool, to present concepts that can not be demonstrated on a two-dimensional blackboard, and as a vehicle for individual student exploration. However, the application of virtual environments always sparks arguments that a simulation is not reality, and that it may have the potential to mislead students about realworld material behavior. In this research project, a virtual-reality geotechnical laboratory is introduced into a graduate-level soil mechanics course. The software is made available to students for individual experimentation, and is assigned for use to complement lecture material about critical-state soil mechanics. Log files are used to identify student usage patterns, and to correlate individual student performance with exploratory use of the environment. Preliminary observations and conclusions based on this pilot project are presented.

Figures (5)

the specimen is loaded to failure in shear, then u durin incre resul expe entirely suitable for this educational setting, whe unde g the test open or close the drainage valve, i NC Cl rstanding of soil behavior under different co ndi nloaded. Instead, the student rease or decrease the cell ase or decrease the shear stress. The student may also reset the test at an ts obtained from a non-traditional stress path rimental test series, where the goal is to expli may not be suitable for a p tly determine the material may at any time pressure, and y time. While the hysical properties, it is re the goal is for the student tions. to gain an intuitive

the specimen is loaded to failure in shear, then u durin incre resul expe entirely suitable for this educational setting, whe unde g the test open or close the drainage valve, i NC Cl rstanding of soil behavior under different co ndi nloaded. Instead, the student rease or decrease the cell ase or decrease the shear stress. The student may also reset the test at an ts obtained from a non-traditional stress path rimental test series, where the goal is to expli may not be suitable for a p tly determine the material may at any time pressure, and y time. While the hysical properties, it is re the goal is for the student tions. to gain an intuitive

The distribution of usage time for individual students is plotted in Figure 3. The log file recorded the time that each student logged in and out of the program. Typically this occurred over multiple sittings. Periods of inactivity of greater than 15 minutes are disregarded in this analysis. The smallest time of total usage was 51 minutes, the largest was 5 hrs. 14 minutes, an the average (mean) time of use was 2 hrs. 27 minutes. There was wide variation in usage times among individual students, but approximately 40% of the class falls in the range from 1 to 2 hrs Because the log utility recorded all user actions and date-time stamped the information, another measure of individual student usage is the disk size of the logged activity. Figure 4 shows the distribution of recorded activity among the students in terms of file size. The smallest file size was 273 kilobytes, the largest was 3.86 Megabytes, and the mean file size was 1.61 Megabytes. While there was again wide variation in file sizes among individual students, there appears to be a cluster in the range from 400 to 800 kilobytes; approximately 30% of the class falls in this range. Because of the large variation in recorded activity, in terms of both time and disk usage, it is evident that students used a number of individual approaches to complete the assignment.

The distribution of usage time for individual students is plotted in Figure 3. The log file recorded the time that each student logged in and out of the program. Typically this occurred over multiple sittings. Periods of inactivity of greater than 15 minutes are disregarded in this analysis. The smallest time of total usage was 51 minutes, the largest was 5 hrs. 14 minutes, an the average (mean) time of use was 2 hrs. 27 minutes. There was wide variation in usage times among individual students, but approximately 40% of the class falls in the range from 1 to 2 hrs Because the log utility recorded all user actions and date-time stamped the information, another measure of individual student usage is the disk size of the logged activity. Figure 4 shows the distribution of recorded activity among the students in terms of file size. The smallest file size was 273 kilobytes, the largest was 3.86 Megabytes, and the mean file size was 1.61 Megabytes. While there was again wide variation in file sizes among individual students, there appears to be a cluster in the range from 400 to 800 kilobytes; approximately 30% of the class falls in this range. Because of the large variation in recorded activity, in terms of both time and disk usage, it is evident that students used a number of individual approaches to complete the assignment.

be more cautious, taking time to reflect on increment and judiciously co over that time can be seen as mo nse, but not necessarily taki for the variation in (recording of move respo expla action nations action as wel load i given Nncreme: common exp student had an individual style of generalizatio test, an as the initial nt size (small d would thus anation for t nN. ment u nsidering thei inal states re explora ng the tim sed very li ttle disk space, whereas load increm of stress and strain) and the student’ incremen ts would require more steps to reach me more disk space). Analysis of the log files the observed behavior resulting from each load rnext action. Students with many logged actions tory, performing actions quickly and observing the e to try to understand the underlyin g meaning. Other time and activity include differences in type of f predominant ents recorded the s preference for failure fora reveals no iation between recorded time and recorded acti working with the program which precludes much vity; rather, each Further evidence of the wide variation in individual styles is shown in Table 1. The indi students are listed in order of increasing time using the program. Column 2 indicates the disk space required to store the text description of their activity. Column 3 indicates whether the log files revealed that the student performed the test series prescribed in the tutorial all student actions were recorded in the log file, it was simple to scroll through the text of the log file and determine whether or not the tutorial was followed. 1 Appendix). Because students attempted to and M) made the mis pressure) to 70 kPa. follow the short tutorial procedure from beginning to end; two of take of changing the preconsolidation pressure (instead of the initi vidual or not see the Ten these (C ial cell Eight students did not attempt to follow the complete tutorial procedure properly. In some cases, there was evidence that the student began to perform the tutorial test series, but quickly deviated from the prescribed path and never completed it.

be more cautious, taking time to reflect on increment and judiciously co over that time can be seen as mo nse, but not necessarily taki for the variation in (recording of move respo expla action nations action as wel load i given Nncreme: common exp student had an individual style of generalizatio test, an as the initial nt size (small d would thus anation for t nN. ment u nsidering thei inal states re explora ng the tim sed very li ttle disk space, whereas load increm of stress and strain) and the student’ incremen ts would require more steps to reach me more disk space). Analysis of the log files the observed behavior resulting from each load rnext action. Students with many logged actions tory, performing actions quickly and observing the e to try to understand the underlyin g meaning. Other time and activity include differences in type of f predominant ents recorded the s preference for failure fora reveals no iation between recorded time and recorded acti working with the program which precludes much vity; rather, each Further evidence of the wide variation in individual styles is shown in Table 1. The indi students are listed in order of increasing time using the program. Column 2 indicates the disk space required to store the text description of their activity. Column 3 indicates whether the log files revealed that the student performed the test series prescribed in the tutorial all student actions were recorded in the log file, it was simple to scroll through the text of the log file and determine whether or not the tutorial was followed. 1 Appendix). Because students attempted to and M) made the mis pressure) to 70 kPa. follow the short tutorial procedure from beginning to end; two of take of changing the preconsolidation pressure (instead of the initi vidual or not see the Ten these (C ial cell Eight students did not attempt to follow the complete tutorial procedure properly. In some cases, there was evidence that the student began to perform the tutorial test series, but quickly deviated from the prescribed path and never completed it.

Column 5 contains the number of times the student “reset” the soil specimen. This is an indication of the number of tests performed, since the student would need to reset after attaining failure under a single test. Approximately half of the students reset the specimen between 60 and 80 times. Two students (R and T) reset the specimen over 150 times. Columns 6 and 7 contain the number of times the student edited the cell pressure and the reconsolidation pressure, respectively. The value i O'o +O ressure three times as often as the preconsolidation 30 as often as the cell pressure (30 vs. 9), indicating m xpended on Question #1, which required the student ressure. Similarly, the value in column 7 is an indi 2, which required the student to vary preconsolidatio ore relative effort on Question #1. Student N edited p UC Other students fell within these two extremes, but th of effort. n column 6 is an indication of tl cation of the effort expended o to study the effect of OCR by n pressure. Student R edited he effo n Ques the cel ressure (110 vs. 37), indicatin g muc the preconsolidation pressure three h more relative effort on Question #2. ere was wide variation in the relative levels rt varying cell tion a times

Column 5 contains the number of times the student “reset” the soil specimen. This is an indication of the number of tests performed, since the student would need to reset after attaining failure under a single test. Approximately half of the students reset the specimen between 60 and 80 times. Two students (R and T) reset the specimen over 150 times. Columns 6 and 7 contain the number of times the student edited the cell pressure and the reconsolidation pressure, respectively. The value i O'o +O ressure three times as often as the preconsolidation 30 as often as the cell pressure (30 vs. 9), indicating m xpended on Question #1, which required the student ressure. Similarly, the value in column 7 is an indi 2, which required the student to vary preconsolidatio ore relative effort on Question #1. Student N edited p UC Other students fell within these two extremes, but th of effort. n column 6 is an indication of tl cation of the effort expended o to study the effect of OCR by n pressure. Student R edited he effo n Ques the cel ressure (110 vs. 37), indicatin g muc the preconsolidation pressure three h more relative effort on Question #2. ere was wide variation in the relative levels rt varying cell tion a times

Table 1. Summary of individual usage styles. IV. Correlation with Performance

Table 1. Summary of individual usage styles. IV. Correlation with Performance

Key takeaways

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  1. The virtual geotechnical laboratory enhances student understanding of soil mechanics through interactive simulations.
  2. Students used the virtual lab for an average of 2 hours and 27 minutes, showcasing varied engagement levels.
  3. The overconsolidation ratio (OCR) significantly influences ultimate load and pore water pressure in soil tests.
  4. Log file analysis reveals diverse student approaches and learning styles in using the virtual lab software.
  5. Future developments aim to integrate structured learning and intelligent tutoring to guide student interactions.

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