Showing papers on "Settlement (structural) published in 1983"

The settlement survey of Tikal

Abstract: This volume is an essential reference in the study of Classic Maya settlement patterns. Maps of four cardinally oriented strips, each extending 12 km from central Tikal, document the survey area. In addition to these major overall maps (at 1:5000), a number of 1:2000 maps cover the many relatively smaller sites. The accompanying text explains the strategy, procedures, and theoretical considerations of mapping systems.

Fundamental results concerning the settlement of a rigid foundation on an elastic medium due to an adjacent surface load

Abstract: This paper examines the interaction between a rigid circular foundation resting in smooth contact with an isotropic elastic halfspace and a concentrated surface load which acts at a finite distance from the foundation. Owing to the action of the external load the rigid foundation experiences an extra settlement and a tilt. The expressions for the extra settlement and the tilt are evaluated in exact closed form. It is also shown that these deformations due to the external load satisfy Betti's reciprocal theorem. The auxiliary solution required for the application of the reciprocal theorem is derived from the analysis of the problem of a rigid circular foundation resting in smooth contact with an elastic medium and subjected to an eccentric load. The, results developed for the interaction between the rigid circular foundation and the external concentrated load are utilized to generate, among others, solutions for the settlement and tilt induced at a rigid foundation due to its interaction with uniformly or non-uniformly distributed loads with circular and square plan shapes.

Deformation phenomena in the area of the no. 7 shop of the Nikopol' Southern Pipe Plant

Abstract: 1. The settlements of shop structures on a deeply compacted bed, which have reached 100 cm, and those of smoke stacks on pile foundations, which have attained 73 cm, cannot be explained by the traditional method as a result of the slump-type settlement of the soils under the combined action of natural and external loadings. These settlements are the result of the development of deformation phenomena that develop over a long period of time in the soil mass under the action of natural pressure and infiltrating water, virtually irrespective of the external loads due to structures. In contrast to familiar slump-type settlement phenomena, these deformation phenomena are developing in a stratum of soils incompletely consolidated under the action of natural pressure and water in both its section prone to slump-type settlement, and in the underlying section not prone to slum-type settlement (as a result of a rise in the water table). Thus, the zone of deformations does not coincide with the slump-type settlement zone, and its upper boundary is situated below the plane of the initial slump-type settlement pressure. Thus, the insufficient density of the soils underlying the stratum prone to slump-tupe settlement, i.e., the stratum incompletely consolidated (under the action of natural pressure and water), is a basic condition for possible development of deformation phenomenon. In the opposite case, wetting of the stratum from above causes a familiar slump-type settlement phenomenon. 2. The development of the deformation phenomenon can be arrested by eliminating the wetting of the soils from above. Under conditions of continuing wetting from above, the deformations can be stabilized by raising the water table to the top of the stratum. 3. Provision for the normal service of structures in regions of possible deformation phenomena is achieved by building structural water-protection measures and by sinking the foundations completely through the entire incompletely consolidated soil stratum. In cases where foundations are installed without completely penetrating the soils in the incompletely consolidated stratum, water-protection and structural measures should be taken in large part.

Settlement of Raft Foundations

Abstract: Recent multistory structures built in the City of Adelaide, South Australia, have frequently been founded on rafts. The authors have measured settlements on three such structures, and on two of the three sufficient exploration and test data were available to permit a review of techniques used for settlement prediction. For two of the projects conventional surveying techniques were used; for the third a borehole extensometer technique developed in the United Kingdom was the primary technique. The extensometer approach was found to be superior from a number of standpoints, including accessibility during construction, convenience of measurement and accuracy of results. An alternative method is proposed for settlement prediction and is demonstrated to be simple, versatile and to give results similar to those obtained from currently used methods that are either more restrictive or more time consuming in their application.

Pile Settlement in Liquefying Sand Deposit

Abstract: Model studies have shown that end-bearing pile settlement in a saturated sand deposit is very sensitive to excess pore pressures induced by earthquake shaking. Settlement amounting to pile failure will be reached before liquefaction occurs, for pile safety factors in the 1.5 to 3 range. Variables considered in the program were effective stress level, relative density and stress history of the sand, diameter and safety factor of the pile. Tests were carried out in an apparatus designed so that the model pile tip could be inserted into a saturated sand mass under effective stress levels of up to 40 psi (276 kPa). Excess pore pressures were then induced by applying cyclic load to the sand in undrained conditions. Tests with piles of three diameters showed consistent behavior when corrected for apparatus boundary conditions. These results may therefore serve as an element of judgement in predicting the behavior of full-size piles.

Thaw Settlement Analysis for Buried Pipelines in Permafrost

Abstract: This paper focuses on determination of allowable thaw settlement for the design of cross country pipelines in permafrost areas. The purpose of the thaw settlement evaluation is to aid in the selection of the proper pipeline construction mode which will ensure pipeline integrity and minimize impact on the environment and adjacent structures. The potential thaw settlement of each pipeline segment is calculated in accordance with the project design criteria and compared to allowable design values. The appropriate construction mode to mitigate adverse settlement is selected for segments where the potential thaw settlement exceeds the allowable design values. Geothermal-geotechnical analyses, which are based on soils information obtained from investigations along the pipeline route, are performed to predict thaw depth over the design life of the system and resulting cumulative thaw settlement potential. The effectiveness of this method is dependent on a well defined soil properties database along the alignment. Design values for allowable thaw settlement are determined from stress analysis for appropriate combinations of pipeline settlement configurations and soil conditions.

The Efficiency of Services in Dispersed and Concentrated Land Settlement: A Comparison

Abstract: The provision of services for small-holders' land settlement entails an efficient spatial organization that will minimize redundancy and maximize the number of consumers per center without impairin...

Settlement considerations in the design of axially loaded piles

Abstract: The paper considers the design process for piles used as settlement reducers, examining the choice of a suitable slenderness ratio taking into account the stiffness of the pile relative to that of the soil and the type of foundation. A simple approximate solution giving the load settlement ratio for a single pile in terms of pile and soil properties is determined. A critical length to diameter ratio proportional to the square root of the stiffness ratio is implied, beyond which increasing the pile length gives little corresponding increase in stiffness of the pile. Designers can then choose piles longer or shorter than this critical length depending on whether the main purpose is to increase the capacity of the foundation or decrease the settlement of the foundation. Because the reduction in skin friction from a peak to a residual value may be great when the pile is subjected to cyclic displacements large enough to break the pile-soil bond at each cycle, a criterion is suggested to ensure that this rupture does not occur. It is recommended that the slenderness ratio chosen is close to the critical value; the radius may then be chosen so that settlement under working load is just sufficient to mobilise peak skin friction at the ground surface giving a factor against overall failure of about 2. (TRRL)

Influence factors for settlement estimates of footings on finite layers

Abstract: The estimation of the settlements of surface footings on finite layers is examined for values of Poisson's ratio ranging from 0 to 0.5. Influence factors based on Steinbrenner's approximate method ...

The effect of yield on the settlement of rigid foundations on clay stabilised with stone columns

Abstract: In this paper the settlement of a rigid foundation supported by a layer of clay which has been stabilised with stone columns is considered. The results of an analytic solution for the settlement, assuming no yield occurs in the clay or columns, have been presented in a previous publication. This solution is now used to develop an interaction analysis which takes account of yielding within the stone columns. This interaction analysis is based on a number of plausible assumptions regarding the behaviour of the clay and columns. In order to check the validity of these assumptions non- linear finite element analyses have been performed and the agreement between the two methods is very good. However, the computational effort required for the finite element analyses is many orders of magnitude greater than that for the interaction analysis. This analysis has been used to generate a number of parametric solutions which provide a basis for estimating the reduction in settlement of the foundation due to the stabilisation of the clay. (Author/TRRL)