Compressibility Determination: Consolidation Test Lab Report Class: CE 3401L - 05: Geotechnical Engineering Laboratory Professor: Masis Markossian Location: University Laboratory 17-1480 Prepared by: Blue Group Quinn Benitez Amy Gilbert David Angel Anes Abdulkarim Olivia Faye Submitted: March 29, 2024 Table of Contents 1. Introduction/Purpose. 2. Materials and Equipment 3. Procedure 4. Results and Calculations 5. Discussion 6. Conclusion 7. References 2 .2 2 3 5 5 .6 1 Introduction/Purpose When building, one must determine the soil compressibility, which means how much the soil deforms when loaded. Appropriate computation requires knowledge of the properties of soil. Engineers commonly use the consolidation test to determine the soil's stress-strain properties, which involves applying a known vertical load to a soil sample. The soil sample is allowed to deform in a vertical direction while it is being constrained in a horizontal direction. The one- dimensional consolidation test allows for vertical strain computation. A stress-strain curve is created by performing a series of loads on a single soil sample. The consolidation tests comprise a series of time-dependent loads performed incrementally using the same soil sample. It is also critical to note that a soil sample does not consolidate and deform to its final state immediately after loading. It takes some time, especially when the soil is saturated. One must create excess pore pressure to force the water to flow out of the soil sample. The consolidation rate is controlled by the hydraulic conductivity and compressibility of the soil. The chapter outlines the procedures for determining soil compressibility. Materials and Equipment • Consolidation cell base w/water bath • Confining ring Small porous stone • Large porous stone ● Loading cap • Steel ball Filter paper • Allen wrench ● Screwdriver • Loading frame ● • Dial gauge Clipboard w/datasheet ● Calibrated weights 2 Procedure For the consolidation test, we are determining how much a soil will deform when loaded. To do this, we used the ASTM D2435 Standard Test Methods for One-Dimensional Consolidation Properties of Soils Using Incremental Loading as described in our lab manual. We used a 1-inch-tall cylindrical undisturbed sample that we enclosed between filter paper a same size porous stone on top and a larger porous stone beneath. That was surrounded by a circular brass confining ring that was tightened with a machine screw to hold the sample in place. We then placed it in a loading frame, with a brass loading cap on top and covered the entire thing in saran wrap, meant to keep moisture in but also removable to add water later. A steel ball is placed on top and then puts the sample assembly in a loading frame. The loading bar is arranged so it sits on the steel ball and compressed 0.3 inches and tightened. The gauge is zeroed out before any weights are added. As we only had six days to complete this lab, we had a different schedule and loading/unloading schedule than standard. We started the first day (Friday) by preparing the sample and loading frame, applied a seating load of 100 lb/ft² and recording the reading of the gauge at 0.1, 0.2, 0.5, 1, 2, 4, 8, and 10 minutes after the weight was added. These are used as seating load readings. We then left the sample over the weekend and returned on Monday to record the gauge, add water until it reached the bottom of the brass loading cap and added another 100 lb/ft² of weight for a total of 200 lb/ft². We then returned on the next day (Tuesday) to record the gauge and double the weight for a total of 400 lb/ft² acting on the sample. On Wednesday, we doubled the load again to a total of 800 lb/ft² after recording the gauge. We started unloading on Thursday, recording the value on the gauge and removing 600 lb/ft² for a total of 200 lb/ft² acting on the sample. On Friday we recorded the final value, removed the remaining 200 lb/ft² weights and cleaned up. Loosening the gauge mount, moving the dial gauge and the loading arm to remove the loading frame, disposing of the sample, and cleaning the equipment. Results and Calculation 3 Date Elapsed Time (min) lb Effective Stress Strain (ε) 3/15/24 0.1 100 -0.0007 66 0.2 100 -0.0006 " 0.5 100 -0.0005 66 1.0 100 -0.0005 66 2.0 100 -0.0002 66 4.0 100 -0.0001 66 8.0 100 -0.0001 66 10.0 100 0.000 3/18/24 3960 200 0.0036 3/19/24 5760 400 0.0057 3/20/24 7200 800 0.0155 3/21/24 8640 200 0.0307 3/22/24 10080 200 0.0270 Table 1: Data Log Strain (ε) 1000 800 600 400 400 200 100 1100 200 0.00 0.01 0.02 Stress (σ) Graph 1: Strain vs Stress 200 200 0.03 0.04 +