Posted in Soil Mechanics

Soil Mechanics Textbook by Tsytovich Available

Up until now the only comprehensive soil mechanics textbook we offered for download was Verruijt’s. We now add to that N. Tsytovich’s Soil Mechanics. Download is at the link or at the book cover below; information on the book is as follows:

This is a textbook in the course of Soil Mechanics for higher-school students of civil engineering and hydrotechnical engineering, and also for students of other specialties associated with construc­tion of engineering structures, such as road constructors, ameliorators, geologists, soil scientists.

The Author has made an attempt to write a concise course on the basis of a wide synthesis of natural sciences and to present the theore­tical data in the most simple and comprehensive form, without depreciating, however, the general scientific aspect of the problem; his other aim was to present a number of engineering solutions of problems in the theory of soil mechanics (calculations of strength, stability and deformability), which might be widely used in engi­neering.

Some problems in the book are discussed from new standpoints which take into account the principal properties of soils: contact shear resistance, structure-phase deformability (including creep of skeleton), compressibility of gas-containing porous water, and the effect of natural compaction of soils.

The book shows some new methods used for determination of characteristics of soils and gives some new solutions of the theory of consolidation and creep of soils, which can be used for predictions of settlement rates of foundations of structures and their time varia­tions; a separate chapter discusses rheological processes in soils and their significance.

Topics include the following:

  1. CHAPTER ONE. THE NATURE AND PHYSICAL PROPERTIES OF SOILS
    • Geological Conditions of Soil Formation
    • Components of Soils
    • Structural Bonds and Structure of Soils
    • Physical Properties and Classification Indices of Soils
  2. CHAPTER TWO. BASIC LAWS OF SOIL MECHANICS
    • Compressibility of Soils. The Law of C o m p a c t i o n
    • Water Perviousness of Soils. The Law of Laminar Filtration
    • Ultimate Contact Shear Resistance of Soils. Strength Conditions
    • Structural-Phase Deformability of Soils
    • Features of the Physical Properties of Structurally Unstable
      Subsidence Soils
  3. CHAPTER THREE. DETERMINATION OF STRESSES IN SOIL
    • Stress Distribution in the Case of a Three-Dimensional Problem
    • Stress Distribution in the Case of a Planar Problem
    • Pressure Distribution over the Base of the Foundation of
      Structures (Contact Problem)
  4. CHAPTER FOUR. THE THEORY OF ULTIMATE STRESSED STA­TE OF SOILS AND ITS APPLICATION
    • Stressed State Phases of Soils with an Increase in Load
    • Equations of Ultimate Equilibrium for Loose and Cohesive
      Soils
    • Critical Loads on Soil
    • Stability of Soils in Landslides
    • Some Problems of the Theory of Soil Pressure on Retaining Walls
    • Soil Pressure on Underground Pipelines
  5. CHAPTER FIVE. SOIL DEFORMATIONS AND SETTLEMENT OF
    FOUNDATIONS
    • Kinds and Causes of Deformations
    • Elastic Deformations of Soils and Methods for Their Determi­nation
    • One-Dimensional Problem of the Theory of Soil Consolidation
    • Planar and Three-Dimensional Problems in the Theory of Fil­tration Consolidation of Soils
    • Prediction of Foundation Settlements by the Layerwise Summa­tion Method
    • Prediction of Foundation Settlements by Equivalent Soil Layer Method
  6. CHAPTER SIX. RHEOLOGICAL PROCESSES IN SOILS AND THEIR SIGNIFICANCE
    • Stress Relaxation and Long-Term Strength of Cohesive Soils
    • Creep Deformations in Soils and Methods for Their Description
    • Account of Soil Creep in Predictions of Foundation Settlements
  7. CHAPTER SEVEN. DYNAMICS OF DISPERSE SOILS
    • Dynamic Effects on S o i l s
    • Wave Processes in Soils under Dynamic Loads
    • Changes in the Properties of Soils Subject to Dynamic Effects
    • The Principal Prerequisites for Taking the Dynamic Proper­
      ties of Soils into Account in Vibrational Calculations of Founda­tions
Posted in Uncategorized

Derivation of Flamant’s Equations for the Elastic Response Under a Strip Load

In the last post I showed the derivation of the elastic response of a soil to a point load using Boussinesq theory. This is a common part of elementary Soil Mechanics courses but it is uncommon to see the derivation.

The same situation exists with strip (continuous) foundations, the elastic solution usually attributed to Flamant. The solution itself also presented in NAVFAC DM 7.01 and Arnold Verruijt’s Soil Mechanics. The derivation is presented below, and comes from the Manual of the Theory of Elasticity, by V.G. Rekach. Some discussion of this solution is in my post Analytical Boussinesq Solutions for Strip, Square and Rectangular Loads and my class presentation is at Soil Mechanics: Elastic Solutions to Soil Deflections and Stresses.

Posted in Academic Issues, Geotechnical Engineering

Derivation of Boussinesq’s Stress and Strain Equations for a Point Load on a Semi-Infinte Space (like soil)

Most Soil Mechanics and Foundations text and reference books (such as NAVFAC DM 7.01 and Verruijt) state the equations for Boussinesq’s point load problem without proof. For those who are interested in how these equations are developed, below is the derivation, taken from Manual of the Theory of Elasticity, by V.G. Rekach, where more detail is given along with the notation, which is different from what we have in the U.S.. The derivation from Rekach is given below.

Posted in Geotechnical Engineering

Manual of the Theory of Elasticity, by V.G. Rekach

An introduction to problems in the theory of elasticity. You can download the book by clicking here. Contents are as follows: Notation Chapter I Theory of Stress I. Static and Dynamic Equilibrium Equations II. Surface Conditions III. State of Stress at a Point Problems Chapter 2 Theory of Strain I. Strain Equations in Orthogonal Co-ordinates […]

Manual of the Theory of Elasticity, by V.G. Rekach
Posted in Geotechnical Engineering, Soil Mechanics

Mexico City’s surprising crisis: the city is sinking

The city with a metropolitan population of over 20 million is sinking at a rate of almost 50 centimeters (20 inches) per year — and this isn’t stopping anytime soon.

At first glance, you’d be inclined to attribute this to the strong earthquakes that sometimes strike Mexico City. But while earthquakes can cause their own damage, they’re not the main culprit here. Instead, it’s something much more inconspicuous: subsidence.

You can read it all here. Put into geotechnical terms, the bed of old Lake Texcoco has some very high void ratio soils, and as a large city puts pressure on them the void ratio decreases as the voids between the soil grains shrink. Thus the entire city has severe settlement, total and differential.

A diagram, from the Swedish geotechnical engineer and academic Bengt Broms, showing how we consider the volume and mass/weight relationships in soil. The particulate matter of the soil means that the soil mass has three components: solid (particles,) water (in the voids) and gas/air (also in the voids.) That simplification is shown above, along with the definition of void ratio.
A diagram, again from Bengt Broms, illustrating the problem in Mexico City and whenever what we call consolidation settlement takes place. The soil particles have been combined into one mass (hatched area.) As pressure is applied, the particles come closer to each other and the volume of the voids decreases, thus we have settlement.
A photo from Mexico City showing the effects of subsidence many years ago. The top of the pole was originally the ground surface before structures were built on it and subsidence started. The photo and an explanation can be found in the textbook Soils in Construction. Needless to say, it’s only gotten worse in the intervening years. Photo courtesy of J.R. Bell.

My own lecture on the subject of settlement and consolidation is here.