Fundamentals of Geotechnical Engineering

Principles of Foundation Engineering and Principles of Geotechnical Engineering were originally published with 1984 and 1985 copyrights, respectively. These texts were well received by instructors, students, and practitioners alike. Depending on the needs of the users, the texts were revised and are presently in their eighth editions. These texts have also been translated in several languages. Toward the latter part of 1998, there were several requests to prepare a single volume that was concise in nature but combined the essential components of Principles of Foundation Engineering and Principles of Geotechnical Engineering. In response to those requests, the first edition of Fundamentals of Geotechnical Engineering was published in 2000. This text includes the fundamental concepts of soil mechanics as well as foundation engineering, including bearing capacity and settlement of shallow foundations spread footings and mats), retaining walls, braced cuts, piles, and drilled shafts

Principles of Foundation Engineering

A must-have resource for all foundation engineering courses, Principles of Foundation Engineering, 9th Edition provides a careful balance between current research and practical field applications as it introduces civil engineering students to the core concepts and applications of foundation analysis design. Throughout this best-selling book, Dr. Das and Dr. Sivakugan emphasize how to develop the critical judgment civil engineers need to properly apply theories and analysis to the evaluation of soils and foundation design. This new edition includes three new chapters that highlight developing topics. This edition also provides a wealth of worked-out examples and multiple new figures that emphasize the skills most critical for students to master as successful civil engineers

Advances in Instrumentation and Monitoring in Geotechnical Engineering

[Extract] Geotechnical instrumentation to monitor the performances of earth and earth-supported structures is increasingly becoming popular. Verification of long-term performances, validation of new theories, construction control, warning against any impending failures, quality assurance, and legal protection are some of the many reasons for geotechnical instrumentation. They are not only used in field situations, but in laboratories too. With the recent advances in materials and technology, and the need for more stringent performance control, there had been significant developments in the recent past in instrumentation and monitoring techniques

Novel adaptation of Marston's stress solution for inclined backfilled stope

In underground mining, it is crucial to consider the arching phenomenon, especially for inclined backfilled trenches and mine stopes. That phenomenon decreases the vertical stress of the fill material, so, the in-site stress has already redistributed itself to the hanging- and foot-walls when the stope was excavated. In such cases, the mobilized resistance due to friction between the granular backfill material and the inclined walls can substantially reduce the pressure at the bottom of the stope, which could have a major impact on the stability of the backfill medium and consequently also on economic aspects. Most of researchers used numerical analysis or Lab. tests to predict both of vertical and lateral stresses in inclined stopes. However, there is a need to investigate analytical solution to describe the behaviour of those stresses in inclined stopes. Based on Marston’s formula, this research provides a new approach to predicting vertical stresses at any depth in inclined backfilled stopes. The proposed approach introduces a new parameter, η, to account for the contribution of backfill arching. This parameter specifies the ratio of normal stresses on the hanging wall and foot wall of the inclined backfilled stope. This differs from previous approaches, which assumed that the normal stress on the inclined backfilled stope's hanging wall and foot wall was equal. To validate the proposed approach, results obtained are compared with numerical, analytical, and experimental results from previous research. It is found that if the proposed parameter, η, is modified to 0.2 for the lateral earth pressure coefficient at rest with an angle of inclination of 60° to 80°, good agreement with experimental data is achieved

Strength and Rheology of Cemented Pastefill using Waste Pitchstone Fines and Common Pozzolans Compared to using Portland Cement

Cemented pastefill is one of the most popular backfill types that use waste mill tailings to backfill and stabilise the mined-out voids in underground mines. Cement dosage in the range of 3–7% is added to the tailings to increase the strength of cemented pastefill to serve as wall support when extracting adjacent stopes. Cement is expensive and contributes significantly to the cost of backfilling even with small dosages. Moreover, the production of cement is energy intensive and contributes to the emission of carbon dioxide. Partial replacement of cement with supplementary cementitious materials can significantly reduce cost and make mine backfilling more environmentally friendly. This paper reports the findings from a laboratory test programme on the optimization of mix designs using fly ash, slag, pitchstone fines, and polycarboxylate plasticizer. Results indicated that apart from common pozzolans like fly ash and slag, the pitchstone fines attained comparable unconfined compressive strength when replacing cement by 10–20%. The findings are useful for the mining and civil industries trying to dispose the mine waste or reusing it as backfill or as construction material

The effect of long-term consolidation on foundations underpinned by micropiles in soft clay

So far insufficient research has been done on the long-term behavior of micropiles embedded in a clay medium, even though this has a significant influence on the expected total settlement. This paper considers a square foundation placed on a clay bed and tested under vertical loads until the clay reached its bearing capacity. Subsequently, the plate was underpinned with four micropiles, and the load test was repeated. These test data were used to validate the coupled hydraulic-mechanical three-dimensional finite difference model presented in this paper. In the numerical modelling, four different load transfer scenarios were considered to simulate different approaches to adding floors to an existing building. Consolidation periods of zero months, six months, and five years between the application of the load due to the existing building, and the application of loads due to additional storeys were considered. The six-month period represents a short-term, and the five-year period a long-term scenario. Following the first consolidation period and the application of loads representing additional storeys, a second consolidation period was implemented, such that the combined length of the two consolidation periods was five years. In this study, the results showed that the installation of micropiles immediately after the completion of existing floors is most successful in controlling the settlement of additional floors later on

Comparison Between Deterministic and Stochastic Interpolation Methods for Predicting Ground Water Level in Baghdad

Surface interpolation techniques are usually used to create continuous data (i.e. raster data) from distributed set of point data over a geographical region. There are deterministic and stochastic (geostatistical) interpolation techniques can be used to create spatial raster surface. In this paper, the comparison between the Inverse Distance Weight (IDW) interpolation method as deterministic method and the Kriging interpolation method as stochastic method is done to determine the best performance for measuring levels of ground water in Baghdad Governorate. Spatial raster surface surfaces as ground water prediction maps are generated from each method by using average ground water level measured at 206 wells in the study area. These maps are shown spatial variation in the ground water levels and they have complete different. The IDW method results a refined map and lesser error than the Kriging method. Thus, the analysis shows that the IDW gives better real performance of measuring levels of ground water in Baghdad Governorate

Preface to special issue on foundations

[Extract] Soil mechanics and foundation engineering go hand in hand. While there were so many new frontiers in different areas (e.g. geosynthetics, environmental geotechnics, instrumentation) related to geotechnical engineering, there have been significant advancements in the core area of foundation engineering during the past few decades. The objective of this special issue is to bring together some recent developments in foundation engineering in all fronts such as analytical studies, model tests in laboratories, and numerical modelling. There are ten papers in this special issue, covering a wide range of topics related to bearing capacity and settlements of foundations. While having the emphasis on shallow foundations, we have also included an interesting paper on piles that deals with the prediction of pile group capacity

ANISOTROPY AND STRESS PATH EFFECTS IN CLAYS

Anisotropy and stress path are two major factors requiring attention in laboratory and in situ testing. In the research reported herein, experimental and theoretical studies were made on these two factors. Experiments were performed in a servo-controlled cuboidal shear device, and analytical studies were based on the Cam Clay and the modified Cam Clay models. When implications of the findings made in this dissertation are discussed, emphasis is given to pressuremeter testing where anisotropy and stress path play a role. However, the results are of a general nature, and apply to other problems as well. Stress anisotropy in consolidation was studied analytically. A simple procedure was developed to predict the in situ or K\sb{\rm o} undrained shear strength from the results of ordinary CIUC tests. The procedure was validated with published experimental data on 24 different soils. To model the in situ behavior of clays, the critical state models, Cam Clay and modified Cam Clay models, were extended to consider the K\sb{\rm o} consolidated initial state. A new state parameter, spacing ratio, was introduced to simplify the analysis. Expressions were developed for undrained shear strength and for Skempton\u27s A-parameter at failure. Plane strain conditions are often assumed in the interpretation of pressuremeter test results in clays. Variation of principal stresses during plane strain compression were studied using the modified Cam Clay model. It was shown that \sigma\sbsp{2}{\prime}/(\sigma\sbsp{1}{\prime} + \sigma\sbsp{3}{\prime}) steadily increases, but only slightly, during plane strain compression, which is in agreement with previous experimental results. For practical purposes it is a good approximation to assume that \sigma\sbsp{2}{\prime}/(\sigma\sbsp{1}{\prime} + \sigma\sbsp{3}{\prime}) is a constant throughout plane strain compression loading. A cuboidal shear device with automatic data acquisition system and servo control, a slurry consolidometer, and appurtenent components were developed. Isotropically or anisotropically consolidated cubical specimens were loaded horizontally or vertically under undrained conditions. A significantly larger \phi\sp{\prime} was observed when the loading was horizontal in direction. Thus, in practice it is necessary to use the value of \phi\sp{\prime} appropriate to the direction of field loading

Geotechnical issues of mining with hydraulic backfills

This paper presents the state of the art of geotechnical engineering issues involved in mining. Of the two methods of extracting ores from the ground, open cut mining and underground mining, this paper concerns itself with the latter: it gives a broad overview of the salient issues related to underground mining with special emphasis on hydraulic backfilling approach