Settlement Back-Analysis of Buildings on Soft Soil in Southern Germany

This paper presents 10 case-histories of buildings on soft clay in southern Germany. A lot of field observations show that the calculated settlements using the routine analysis are on average 50 % larger than settlements actually measured in this area. A back-analysis is carried out to verify the soil parameters which are intended to investigate in the subsurface exploration phase and later in a laboratory test program. Recommendations for the engineering practice are suggested to review the determination of compressibility parameters and, consequently, to improve the settlement prediction

Stabilisation of river dykes with drainage elements

In recent times, enormous damage has been caused by dyke failures during and after river flood disasters throughout the world. Besides extreme meteorological conditions the reasons for these failures are inadequate design and the actual condition of affected dyke structures. <br><br> To minimize the occurrence of dyke failures in future, in a national BMBF research project (BMBF: German Federal Ministry of Education and Research) an alternative stabilisation technique has been investigated as an instrument for short term refurbishment and as an improvement to existing and endangered dyke structures. <br><br> It is intended to improve the stability of dyke structures by the mechanical installation of drainage devices, thus preventing dyke failure by controlling the seepage in the structure. <br><br> Within the scope of this paper selected results concerning stabilizing capability and feasibility of the stabilisation technique are presented in detail. Concerning feasibility the focus is placed on natural scale model tests to verify numerical calculations and to investigate the suitability of the adapted installation methods in situ

Numerical analysis of piled embankments on soft soils

The construction of embankments on soft soils is a common problem. Soft soil cannot sustain external loads without having large deformations. Piled embankments system provides a possible solution for the construction of roads and railways over soft soils. Until now, the system behaviour could only be described by analytical models such as those included in British or German codes. This paper describes research undertaken to investigate the effects of pile embankment construction in soft soils. Experimental results are used to help investigate arching effect developed due to differential settlement between pile and surrounding soft soil. A numerical parametric study was carried out to examine the impact of various soil parameters on the pile-embankment system behaviour. The outcome of the parametric study implemented using numerical analysis has been investigated and discussed throughout this paper. Based on the numerical analysis carried out in this research, it was found that the earth pressure coefficient normalized by the passive earth pressure Kp plotted on a vertical profile at the midpoint between piles can give a good illustration of arching behaviour. The findings presented in this paper can be considered as guides for numerical analysis and design criteria of soil arching for embankments constructed over piles

The Deformation and Degradation of Granular Material under High-Frequency Cyclic Loading

© ASCE. In order to understand the permanent deformation and degradation of railway ballast under high speed train loading, a series of cyclic triaxial tests were conducted using large-scale cylindrical apparatus. The frequency was used from 5 Hz to 60 Hz corresponding to the train speeds from about 40 km/h to 400 km/h. Three types of permanent deformation mechanisms were observed in response to the applied cyclic loads, namely, plastic shakedown at relatively lower frequency, ratcheting at an increased frequency, and plastic collapse at higher frequencies. Correspondingly, four types of particle degradation were observed. The magnitudes of ballast deformation and degradation were found to increase with the frequency and number of load cycles. A critical train speed was identified. Moreover, a good correlation was obtained between particle breakage and volumetric strain under cyclic loading