GeoShanghai 2024 Proposal for Short course
Title: Simple methods to rapidly characterize and model unsaturated soil behavior
Topic: Unsaturated soils
Length: Full-Day (8 hours)
Handouts: Printed handouts, Excel spreadsheets will be mailed to participants, videos on YouTube
Description:
Although significant progress has been made in the past six decades, unsaturated soil mechanics is not extensively used in routine engineering projects for several reasons: (1) the equipment needed to characterize unsaturated soils is expensive (60-150k), (2) the suction-controlled tests are time-consuming (1-3 months/soil, 3-5 years/soil), and (3) the theories for unsaturated soils are complicated to understand and model.
This short course will introduce simple methods to rapidly characterize and model unsaturated soils as follows: (1) A Modified State Surface Approach (MSSA) is used to explain unsaturated soil behavior, which can be easily understood by engineers without previous background in constitutive modeling. (2) Conventional testing equipment (single-cell triaxial, oedometer, and unconfined compression test apparatus) for saturated soils is used to rapidly characterize unsaturated soils (4-8 hours/test, 1-2 weeks/soil). (3) Step-by-step procedures are given to analyze these results for constitutive modeling purposes without sacrificing the theoretical accuracy. (4) Discussions on some important topics such as selection of stress state variables for unsaturated soils. The well-known Barcelona Basic Model (BBM) will be used to demonstrate the proposed methods.
Learning Objectives: Technical scope and justification:
This short course contains 5 major parts (presentations):
1. Elasto-plastic theory for unsaturated soils. The BBM will be explained according to conventional approach and MSSA;
2. Laboratory tests to characterize unsaturated soils, suction-controlled tests versus rapid constant water content tests using conventional testing equipment (single-cell triaxial, oedometer, and unconfined compression test apparatus) for saturated soils;
3. Step-by-step procedures to analyze the above results to calibrate the model parameters for the BBM;
4. Predicting soil Reponses at the element levels using conventional approach and MSSA.
Lead Instructor:
Xiong Zhang, Ph.D., P.E.
James A. Heidman Professor, Department of Civil, Architectural, and Environmental Engineering, Missouri University of Science and Technology, 135 Butler-Carlton Hall, 1401 N Pine St., Rolla, MO 65409-0030
Email: zhangxi@mst.edu; Phone: 573-341-6286