Abstract The boulder clay in Glasgow (Scotland) was found to be stiff and ranging from clay size to big rocks (boulder), this makes the sampling process difficult due to the existence of both stones and fissures in the till. Laboratory testing is often unsatisfactory; this led to testing the boulder clay at the site. The pressuremeter with a large diameter was found to be one of the reliable solutions for assessing the strength and consolidation properties of the Glasgow till. The research presented a new large pressuremeter developed enabling to test a representative and satisfactory fissured till in situ. Different methods were adopted to evaluate the undrained parameters of the till from pressuremeter tests. Cyclic loading pressuremeter tests were conducted to explore the effect on the modulus of deformation. Field values of the undrained shear strength and Young's modulus of the boulder clay showed marked increases on those from undrained triaxial tests. Changing the rates of expansion of the probe of the pressuremeter, the membrane showed distinctive effects on the undrained modulus, while no effects on the undrained shear strength and limit pressure. Menard conventional incremental pressure gives lower undrained parameters than those from the constant rate of expansion pressuremeter tests. In situ horizontal coefficient of consolidation is obtained from “diameter holding” tests. The horizontal coefficient of consolidation is found to be affected by changing the rate of the probe expansion. A new method is developed for determining the horizontal coefficient of consolidation from pressuremeter testing. The new method explored values of the horizontal coefficient of consolidation close to those evaluated from the “diameter holding" tests. The values of the in situ horizontal coefficients of consolidation were found to be larger than those evaluated from laboratory-tested samples.
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