Monthly Review of Geotechnical Journals - Up to July

I have been following many geotechnical journals for some time and I have thought that sharing some of the papers that I have interested would be a good idea. It would be a personal note to answer "Where did I see this?" and a way to share updates with geotechnical community. The selected papers are solely based on my research and professional interest, therefore, you may miss some of the good stuff still. But, these short summaries will help you even though. Although I have written "Up to July" in the headline, as most of the journals publish beforehand, you should interpret this as "papers I have access up to July". For example, September 2018 issue of Journal of Geotechnical and Geoenvironmental Engineering is already out there and I have included all the materials that were published. I hope to publish these reviews every one or two month if I get the time.

• Guo, W., Chu, J., & Nie, W. (2018). Design chart for the modified hyperbolic method. Soils and Foundations, 58(2), 511-517.

There are several methods to estimate the final consolidation settlement if you have observed the settlements up to a time after loading. Asaoka method is one of the most common and I have used it before for embankments and buildings. See Asaoka (1978) and Mesri & Huvaj-Sar?han's (2009) papers for details. One of the other methods is hyperbolic method and modified hyperbolic method. This paper develops a simpler approach to use modified hyperbolic method with drains to accelerate settlement. Authors state they have reduced the many parameters into single parameter, vhv, which is the ratio of time factors in horizontal and vertical directions. Using this parameter and observed settlement-time data, it is easier to estimate complete settlement vs. time graph. Remember this paper if you have highly consolidating soils.

• Cunha, R. P., & Poulos, H. G. (2018). Importance of the Excavation Level on the Prediction of the Settlement Pattern from Piled Raft Analyses. SOILS AND ROCKS, 41(1), 91-99.

Although Brazil's Soil and Rocks journal (published by Brazilian Association for Soil Mechanics and Geotechnical Engineering and Portuguese Geotechnical Society) was not on my watchlist (it is now!), my special attention to Prof. Poulos' works have led me to there. Cunha and Poulos' study is on a topic I have special interest for: Compensated piled rafts. They have analyzed a rather not-well-documented case of Hansbo. Using simplified approach to model compensation effects, i.e. reducing building load, they have reached the observed settlements with a Class-C prediction. Soil and Rocks is an open-access journal and related issue can be reached from here.

• Poulos, H. G. (2018). A review of geological and geotechnical features of some Middle Eastern countries. Innovative Infrastructure Solutions, 3(1), 51.

Poulos, again. He presents a perfect summary of his experience and literature review of the published information of geotechnical and geological on Middle Eastern countries. If you ever have a project in Middle East, make sure you have read this paper.

• McGann, C. R., Bradley, B. A., & Jeong, S. (2018). Empirical Correlation for Estimating Shear-Wave Velocity from Cone Penetration Test Data for Banks Peninsula Loess Soils in Canterbury, New Zealand. Journal of Geotechnical and Geoenvironmental Engineering, 144(9), 04018054.

McGann et.al. develops a "loess-specific" correlation for estimating shear wave velocity using CPT. They have collected seismic piezocone (SCPTu) data from 26 loess site in Banks Peninsula, Christchurch, New Zealand. Although we have PEER's extensive collection of Vs correlations, it is important to have loess-specific correlation since these soils are most problematics both for settlement and liquefaction.

• Zhao, S., & Deng, L. (2018). Analyses of embedded piles reinforced landslides using strength reduction finite element method. International Journal of Geotechnical Engineering, 12(4), 389-401.

Zhao and Deng presents effective length approach for piles to support landslides. I was not aware of this approach, however, authors have conviced me to give it a try. The "embedded piles" in the headline is not embedded beams we know from FEM, but piles below the ground level. They introduce effective length of pile, which is the length of the pile above the shear band (failure surface). They have presented a scheme to obtain the optimum effective pile length and used this scheme to improve a real landslide. Authors also claim that bending moment and lateral forces are also reduced using optimum pile lengths instead of full length.

• Zhang, F., Leshchinsky, D., Gao, Y., & Yang, S. (2018). Three-Dimensional Slope Stability Analysis of Convex Turning Corners. Journal of Geotechnical and Geoenvironmental Engineering, 144(6), 06018003.

Authors have presented results of 3D limit equilibrium analyses for convex corners of a slope. One interesting conclusion I was really impressed was the following: "...the calculated results demonstrate that even a slight decrease of the turning angle from 180°, representing practical geometrical imperfection, will yield failures having well-defined length. It could be one reason why observed failures have distinctive limited length in seemingly long straight homogenous slopes." I think an experiened geotechnical engineer would not be so keen about using stability charts instead of analyzing the slope. However, these conclusions can be very important to understand some cases.

• Teng, F., Arboleda-Monsalve, L. G., & Finno, R. J. (2018). Numerical Simulation of Recent Stress-History Effects on Excavation Responses in Soft Clays. Journal of Geotechnical and Geoenvironmental Engineering, 144(8), 06018005.

In their paper, Teng et. al. proved the effect of stress-history on the excavation deformation and ground settlement behind excavation using hypoplasticity model of Masin. To be honest, I haven't observed anything new in this paper since we are aware of the effect of history of the soil on the geotechnical performance since Simpson's brick model, even before it. However, since this is a technical note, it is nice to see the same results with hypoplasticity model.

• Al Ammari, K., & Clarke, B. G. (2018). Effect of Vibro Stone-Column Installation on the Performance of Reinforced Soil. Journal of Geotechnical and Geoenvironmental Engineering, 144(9), 04018056.

Al Ammari and Clarke presents a cavity expansion approach to model stone column installation effects. They model stone columns using cavity expansion theory in Plaxis 2D and using the data from 2D analyses, they analyze a case using Plaxis 3D. Their results indicate that coefficient of lateral earth pressure and stiffness may increase up to 6D distance where D is the column diameter. Using this approach, stiffer response, thus less settlement is obtained. Calculated results agree with the observed settlements.

• Kumar, S., & Basudhar, P. K. (2018). A Neural Network Model for Slope Stability Computations. Géotechnique Letters, 1-20.

Kumar and Basudhar developed a neural network to predict factor of safety of a slope. They introduced a formula using weights and bias functions of their model too. R2 values show that simple slope stability problems can be modeled using ANN with a high accuracy.

• Adamidis, O., & Madabhushi, S. P. G. (2017). Deformation mechanisms under shallow foundations on liquefiable layers of varying thickness. Géotechnique.

Authors have compared centrifuge test results of buildings on liquefable layers with common methods to estimate building settlements. Their results show that these common methods such as Tokimatsu & Seed (1987), Liu & Dobry (1997) etc. "failed to offer reliable values." They also note that for deep layers, soil moves downward for depth of B and moves laterally below that point. For shallow layers, soil moves laterally to cause settlement, similar to bearing capacity failure. They also note that Bertalot et. al. (2013) method to estimate upper limit of settlement were valid for the measured settlement below the building.

• Books

Highly respected Arnold Verruijt from Delft have published "An Introduction to Soil Mechanics" which is an extension of his previous lecture notes on this topic. Title may be misleading since this is definetely not an entry level introduction, however, Verruijt's insights on the soil mechanics, as well as on the Computational Geomechanics, carry great importance.

Although I have several, I am always happy to see correlation books. These are life savers during tight scheduled design works. Verbrugge and Schroeder have published "Geotechnical Correlations for Soils and Rocks". I haven't got the chance to see the full book yet, however, quick look is very promising.