The soil-grout interface friction was measured to be in between 0.0 [kPa] and 14 [kPa]. To measure this friction, a special research method was invented that enabled a tunnel to be recreated. With this setup, any formation could be used. The formation could be created with a hole in the middle which simulated a borehole. Next, by filling and pressurising this hole with a bentonite-water suspension, a stable borehole could be simulated. This borehole was then filled with drillgrout to recreate a tunnel filled with grout. This grout column could then be pulled out of the soil formation so that the friction between the drillgrout and soil could be measured. In this setup, no normal forces were present. Due to the absence of normal forces no friction angle could be deducted which made it impossible to estimate the effect of the friction at the depth where a pipe laid by HDD would generally be found. It was concluded that based on the data found, it is not recommended to use grout as a borehole filling around heat transportation pipes. Although the friction would be mainly determined by the filter cake strength, which is comparable to a weak clay, effects like irregular borehole diameters and large soil stresses at the depth of the pipe, would create a frictional force that is large enough to cause buckling or failure of the insulating PUR layer.

This thesis describes the research about the effect of movement on fluid mud. This was done by exposing several samples of fluid mud from the port of Hamburg to different types of movement for an extended amount of time. It was found that when fluid mud is exposed to kinetic energy of the type used in this experiment, particles will arrange themselves. Dense material and larger particles can be found lower than less dense material and smaller particles. The amount of kinetic energy has no effect on the settling velocity once fluid mud settles. In this research energy level 6 created waves with a frequency of about 3 to 4 waves per second with an amplitude of 1.5 cm. This is the least amount of kinetic energy needed to keep the fluid mud homogenised. A lower density fluid mud will settle faster than a higher density fluid mud. It is not yet clear if this is caused by the density, or that the relation of the difference in density and settling velocity is coincidental.