Investigation of aperture penetration of transient fields into a cylindrical cavity

Cellular steel-tube-confined concrete (CSTCC) targets show improved anti-penetration performance over single-cell STCC targets due to the confinement effect of surrounding cells on the impacted cell. Dynamic finite cylindrical cavity-expansion (FCCE) models including radial confinement effect were developed to predict the depth of penetration (DOP) for CSTCC targets normally penetrated by rigid sharp-nosed projectiles, and stiffness of radial confinement was achieved with the elastic solution of infinite cylindrical shell in Winkler medium. Steady responses of dynamic FCCE models were obtained on the assumption of incompressibility of concrete, failure of comminuted zone with Heok–Brown criterion and two possible response modes of the confined concrete in the impacted cell. Furthermore, a DOP model for CSTCC targets normally impacted by rigid projectiles was also proposed on the basis of the dynamic FCCE approximate model. Lastly, relevant penetration tests of CSTCC targets normally penetrated by 12.7 mm armor piecing projectile (APP) were taken as examples to validate the dynamic FCCE models and the corresponding DOP model. The results show that the DOP results based on dynamic FCCE model agree well with those of the CSTCC targets normally penetrated by rigid conical or other sharp-nosed projectiles.

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Quantitative Evaluation of Ground Movements Caused by Grouting during Shield Tunnelling in Clay

Advances in Civil Engineering ◽

10.1155/2019/7498367 ◽

2019 ◽

Vol 2019 ◽

pp. 1-7

Author(s):

Zhi-Feng Wang ◽

Wen-Chieh Cheng ◽

Ya-Qiong Wang

Keyword(s):

Cylindrical Cavity ◽

Radial Stress ◽

Soft Soil ◽

Tunnel Construction ◽

Reliable Measure ◽

Simple Method ◽

Ground Movements ◽

Tunnel Boring ◽

Shield Tunnelling ◽

London Clay

Grouting has been deemed as one of the most effective measures for mitigation of ground movements during tunnel construction in soft soil. Notwithstanding that, a reliable measure to quantitatively evaluate the grouting-induced ground movements during shield tunnelling in soft soil has not yet been developed. This paper presents a simple method capable of quantitatively estimating the ground movements associated with grouting for tunnel-boring operations where the grouting parameters and soil properties are taken into consideration. The grouting process is simplified as the expansion of a cylindrical cavity with a uniform radial stress applied at soil-grout interface in a half plane, and the analytical solution proposed by Verruijt is introduced for determining the ground movements by the expansion of the cylindrical cavity. The proposed method is verified with a case history undertaken in London Clay. The results obtained suggest that this procedure would be helpful in managing the grouting parameters adopted in upcoming soft ground tunnelling project and mitigating the environmental impacts on nearby properties.

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Numerical Integration of the Navier-Stokes Equations for a Disk Rotating in a Housing

Zeitschrift für Naturforschung A ◽

10.1515/zna-1985-0802 ◽

1985 ◽

Vol 40 (8) ◽

pp. 789-799 ◽

Cited By ~ 1

Author(s):

A. F. Borghesani

Keyword(s):

Boundary Layer ◽

Cylindrical Cavity ◽

Boundary Layer Thickness ◽

Stokes Equations ◽

Fluid Motion ◽

Rotating Disk ◽

Infinite Medium ◽

Navier Stokes ◽

Navier Stokes Equations ◽

Viscous Torque

The Navier-Stokes equations for the fluid motion induced by a disk rotating inside a cylindrical cavity have been integrated for several values of the boundary layer thickness d. The equivalence of such a device to a rotating disk immersed in an infinite medium has been shown in the limit as d → 0. From that solution and taking into account edge effect corrections an equation for the viscous torque acting on the disk has been derived, which depends only on d. Moreover, these results justify the use of a rotating disk to perform accurate viscosity measurements.

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