Year Number of Pages Publisher ISO. Additionally, the Eq. The linear function of Eq. Nevertheless, it seems to overestimate the undrained shear strength at a higher range of the net limit pressure. The best fit dashed line resulting from the regression analysis is also plotted in Fig. The tendencies of both the Ei and Eur show an approximate linear increase with depth. However, the linear relationships are clearly separated between the soft and stiff clay layers.
In general, the Eur values are 2 and 3. When the Ei values are compared with the E50 obtained from the CK0U triaxial tests, they seem to locate on the upper values of E This outcome is possibly due to the lesser degree of soil disturbance caused by the LLT tests. The study deals with three main geotechnical parameters: coefficient of earth pressure at rest Ko , undrained shear strength su and pressuremeter moduli Ei and Eur.
The following conclusions are drawn. None of the methods, studied here, give reasonable value of K0 for soft clay layer. As a result, the non-linear correction such as Eq. Therefore, this might be a better choice when it comes to the selection of stiffness modulus.
However, care must be taken in terms of the determination of initial pressure, where Ei is obtained. The second author would like to thank Dr. References Bergado, D. Briaud, J. Balkema, Netherlands. Clarke, B. Gibson, R. Publications Works and Rev. Hawkins, P. Houlsby, G. Huang, W. Mair, R. Marsland, A. Palmer, A. Prust, R. Schnaid, F. Shuttle, D. Surya, I. Teparaksa, W. Timoshenko, S. Wroth, C. Yu, H. Balasubramaniam By Arumugam Balasubramaniam. Yimsiri2, C. As seen in Fig. The geological units can be parameters into foundation design.
Schnaid et al. One of the sub- characterizing the properties of such soils using laboratory units consists of silt, marl and clay, while the second tests is complicated due to the effects of suction. The standard penetration test SPT is the in situ test Where observed, the unsaturated geological units contain most commonly used to investigate the properties of silt, lenses with variations in grading both vertically and clay, sand and coarse sand, but it is not effective for coarser horizontally.
The soil type and structure were recorded and used in the calculation. The guard cell membranes are SPT and PMT tests were undertaken in similar material at inflated by pressurized gas, while the middle membrane is depths of 1. The pres- the parameters obtained by the different tests carried out in sure in all of the cells is incrementally increased and alluvial sand, silt and clay soils. The measured volume In this study, the SPT test was performed in accordance change of the middle membrane is plotted against the with ASTM D , using a standard split-spoon applied pressure and the results of the test expressed in sampler and a In mm.
The penetration resistance for the first mm is the pseudo-elastic zone, the relationship between cell vol- ignored, as the soil is considered to have been disturbed by ume and pressure is virtually linear. The figure shows the the boring of the hole. The N value is the cumulative total pressure-to-volume change generated. The Em utilized to of the blows for each 75 mm penetration after the seating compute the settlement of the soils was calculated using the blows the first mm.
The pL pressure at which , which uses a cylindrical probe placed at the desired failure occurs was defined as the pressure necessary to depth in a pre-bored hole. The pressuremeter dimensions expand the probe to twice its original volume 2Vo for a have not been standardized, which may lead to errors when borehole pressuremeter test, and this can be used directly to attempting to compare test data from different probes.
The pL was also Commonly a 76 mm diameter probe is used, and this computed and interpreted from the test data in order to approach was followed in the present study. You want the aggregate to be completely inundated, so if it is necessary add additional water until it is covered. After each layer of aggregate you add, you will also need to rod the upper 1 inch of aggregate times, and tap the sides of the bowl a few times.
When you have all the aggregate added it will sit for a period of time about equivalent to the time between water going into the mixer and the time of performing the air test.
Before you put the cover on, you will screw a straight tube into the bottom of one of the petcocks and a j-shaped tube into the top of that petcock. Then, you will do your air content on that aggregate mixture, following the steps of the procedure above from step 4 onwards to the point where the air is released into the bowl, step 8. Then, you will remove water from the air meter and put it into your calibration vessel, by releasing water out of the J tube.
The water in the calibration vessel represents the percentage of air in the aggregate that was entrapped and has now been removed. Pressure meters need to be calibrated often. We calibrate ours every 3 months. Your lab technician will call you and tell you to bring it in, and the calibration procedure in Annex A-1 of the ASTM will be performed. It will be helpful for you to read this annex as it can help you troubleshoot problems with the pressure meter.
If any of these problems occur before calibration do not hesitate to bring it in and have your lab tech take a look. It is vital to get the correct air content on tests and unfortunately the pressure meter is one of the most sensitive pieces of equipment. PLEASE keep your pressure meter clean, and check it over before every day of testing to make sure it is working properly.
Take pride in your work and keep your equipment clean and operating smoothly.
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