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<p>Acknowledgement  VII</p> <p>Foreword  IX</p> <p>List of symbols used  XV</p> <p>I. Greek symbols  XV</p> <p>II. Latin symbols  XV</p> <p><b>1 Basics  1</b></p> <p>1.1 Basics and technical implementation of bentonite lubrication systems  1</p> <p>1.2 Annular gap lubrication in pipe jacking  5</p> <p>1.3 Preliminary remarks about the ground 6</p> <p><b>2 Bentonite and bentonite suspensions   9</b></p> <p>2.1 Composition and structure 9</p> <p>2.2 Hydration behaviour   10</p> <p>2.3 Card house structure and thixotropy  11</p> <p>2.4 Yield point, viscosity and gel strength  12</p> <p>2.5 Stability 17</p> <p>2.6 Usual types of bentonite   19</p> <p><b>3 Additives 21</b></p> <p>3.1 Polymers  21</p> <p>3.2 Types of polymer additives   24</p> <p>3.3 Overview of polymer additives and their functions   27</p> <p><b>4 Correct preparation of bentonite suspensions  29</b></p> <p>4.1 Mixing   29</p> <p>4.2 Mixing equipment 33</p> <p>4.3 Mixing instructions  34</p> <p>4.4 Hydration tank 35</p> <p><b>5 Properties of the suspension and measurement processes  37</b></p> <p>5.1 Viscosity: Marsh funnel   37</p> <p>5.2 Yield point: ball-harp rheometer  40</p> <p>5.3 Viscosity and gel strength: Rotational viscometer  42</p> <p>5.4 Filtrate water and thickness of filter cake: filter press  43</p> <p>5.5 Density 45</p> <p>5.6 Water hardness: test strips 46</p> <p>5.7 pH value  46</p> <p>5.8 Conductivity 46</p> <p>5.9 Temperature  47</p> <p><b>6 Ground and groundwater 49</b></p> <p>6.1 Geology of solid rock 49</p> <p>6.2 Geology of soils 65</p> <p>6.3 Stability and stand-up time   85</p> <p>6.4 Hydrogeology  88</p> <p>6.5 Influence of various rock properties on the use of bentonite  99</p> <p>6.6 Contamination in the ground, groundwater or mixing water  100</p> <p><b>7 Bentonite suspensions for annular gap lubrication  105</b></p> <p>7.1 Size of the annular gap  105</p> <p>7.2 Vertical position of the pipe string in the driven cavity  107</p> <p>7.3 Functions of the lubricant in the annular gap 111</p> <p>7.4 Adaptation of the bentonite suspension to the ground 119</p> <p>7.5 Rheological parameters of the bentonite suspension 124</p> <p>7.6 Suspension quantities 132</p> <p>7.7 Time-dependant loss volumes 147</p> <p>7.8 Lubrication strategies 148</p> <p><b>8 Lubrication technology  155</b></p> <p>8.1 Arrangement and spacing of the lubrication points in the pipe string 155</p> <p>8.2 Number and arrangement of the injection fittings per lubricating point in the pipe cross-section   156</p> <p>8.3 Non-return valves  157</p> <p>8.4 Lubrication circuit   158</p> <p>8.5 Interaction between the support pressure at the face and the annular gap pressure  159</p> <p>8.6 Bentonite supply in the starting area  160</p> <p>8.7 Lubricant pressure, lubricant quantity and pressure losses   161</p> <p><b>9 Reporting 163</b></p> <p>9.1 Which parameters should be documented for bentonite lubrication?  163</p> <p>9.2 Forms  163</p> <p><b>10 Lists of the required injection quantities  167</b></p> <p>10.1 Explanation of the lists  167</p> <p>Literature 197</p>

Steffen Praetorius is a graduate geologist and deputy manager of research and development in the Utility Tunnelling department of Herrenknecht AG. In addition to research projects and geotechnical considerations, his duties also include technical and user-specific questions about the use of bentonite in tunnelling.<br> <br> Dr. Britta Scho?er is a researcher and lecturer at the Ruhr University, Bochum at the Chair of Tunnelling and Construction Management. The investigation of bentonite suspensions for construction use in utility construction and tunnelling belong to her specialist areas.

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