摘要:

AbstractPersistent pumping of groundwater is known to cause subsidence of the ground surface. When the soil is composed of alternating layers of sand and clay, subsidence is, in general, a consequence of pressure change in and deformation of all layers. Even with various simplifications, the mathematical task for the mechanics of a layered soil is complex and, in the past, many idealizations have been introduced in the literature. Among the existing approximations, a well‐known approximation by Hantush1for well‐hydraulics in leaky aquifers is intuitively attractive. He used the fact known to be strictly true for simple flows in a soil system with horizontal layers, that the flow must be mainly horizontal in a relatively porous aquifer and mainly vertical in a highly impervious aquitard, and invoked the same approximation for transient flows induced by well‐pumping. In this paper we shall apply a perturbation analysis to give a mathematical confirmation of the hydrological approximation and to show its degree of accuracy. In particular, we treat a three‐layered system, where the middle layer is a relatively soft aquitard, and the well withdraws water from the artesian aquifer at the bottom. The upper aquifer has a phreatic surface. Physically, we examine the often ignored effects of self‐weight which is important for thick aquitards. The perturbation theory is worked out for sufficiently weak pumping rates and small soil deformation. Subsidence in the vertical direction due mainly to the deformation of the soft aquitard is studied. Results show that the common assumption of constant total stress with respect to depth is valid only when the storage coefficient is v

ISSN:0363-9061    

DOI:10.1002/nag.1610160302

出版商:John Wiley&Sons, Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractA model for vibro‐driving of rigid piles in sand is proposed incorporating the interaction of the vibrator–pile–soil system. The vibro‐driver force and the non‐linear soil resistance (dynamic f–w and q–w relationships) have been quantified in terms ofin situstress, relative density and particle size. The influence of relative density (0·65 and 0·90), particle size (effective grain size of 0·2 mm and 1·2 mm) and in situ stress (up to 20 psi) on the vibro‐driving of a closed‐ended pipe pile was investigated experimentally using a large‐scale laboratory testing system. The vibro‐driving model predicted the observed driving history reasonably well. A computer program (UHVIBRO) has been developed to analyse vibratory pile driving using the dynamic soil resistance relationships developed along with correlation factors from the sy

ISSN:0363-9061    

DOI:10.1002/nag.1610160303

出版商:John Wiley&Sons, Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractSecond‐order universal kriging is proposed as an accurate model for interpolating displacements measured in the field to nodal points of a superimposed finite element mesh. These interpolated displacements are used in a modified finite element procedure to calculate strain. This model is compared to a local trend model to judge superiority. Interpolation models are tested by randomly sampling displacements obtained in a finite element analysis, then applying interpolation in attempts to reconstruct the original result

ISSN:0363-9061    

DOI:10.1002/nag.1610160304

出版商:John Wiley&Sons, Ltd    

年代:1992

数据来源: WILEY

ISSN:0363-9061    

DOI:10.1002/nag.1610160305

出版商:John Wiley&Sons, Ltd    

年代:1992

数据来源: WILEY

ISSN:0363-9061    

DOI:10.1002/nag.1610160306

出版商:John Wiley&Sons, Ltd    

年代:1992

数据来源: WILEY

ISSN:0363-9061    

DOI:10.1002/nag.1610160301

出版商:John Wiley&Sons, Ltd    

年代:1992

数据来源: WILEY