Dynamic installation of a torpedo anchor in two-layered clays

Abstract

The behaviour of a torpedo anchor during dynamic installation in two-layered nonhomogeneous clay sediments was investigated through large-deformation finite-element (LDFE) analyses. Parametric analyses were undertaken varying the top layer thickness and strength ratio between two layers. Results show that the location of the demarcation point between the acceleration and deceleration phases of the anchor in the soil relative to the layer interface is the key factor directing the anchor behaviour in layered soils including the final embedment depth. Broadly speaking, the anchor behaviour in soft-over-stiff clay deposits is somewhat similar to that in single layer clay with strength increasing with depth. In stiff-over-soft clay deposits, the anchor penetrates deeper where the anchor deceleration phase (or the demarcation point) falls within the soft layer. Where the demarcation point lies within the top stiff layer, the anchor penetration depth decreases with increasing strength ratio, and the anchor penetration is terminated between the two layers for strength ratios ≥15. For assessing the anchor embedment depth in two-layered fine-grained ocean sediments in the field, an extended total energy–based method, along with a design expression, is proposed.

Loading performance of fish and OMNI-Max anchors in crust-over-soft clays

“…3D LDFE analyses were carried out using the coupled Eulerian-Lagrangian (CEL) approach in the commercial finite element package ABAQUS/Explicit [18]. Extensive background information about installation modelling of anchors in two-layer clays can be found in Kim et al [6], which are not repeated here.…”

“…the clay is one to two orders of magnitude stronger than a virgin deposit) is commonly encountered in both shallow and deep waters in the West coast of Africa, the Sunda Shelf, offshore Malaysia, Australia's Bass Strait and North-West Shelf [1][2][3][4][5]. Kim et al [6] provided a summary of site investigation data for layered seabed sediments with a surface or interbedded crust layer.…”

“…No attempt has been taken to install dynamically installed anchors in layered soils with a crust layer. Recently, Kim et al [6] assessed the embedment depth of a torpedo anchor in crust-over-soft clay deposits through numerical analyses. Their results showed that the anchor can penetrate through the crust layer with thickness 0.25L A (where L A is the length of the anchor) and strength ratio to the bottom soft layer > 15.…”

Numerical Experiment Research on Failure Characteristics of Anchored Rock With Negative Poisson’s Ratio Bolt

“…Bolt is a kind of supporting body that transmits tensile load to the stable rock layer to improve the stability and strength of the rock medium, bolt has a lower cost in terms of material and manpower, so it has been widely used in mining, transportation, water conservancy and urban underground space engineering [1][2][3][4]. With the development of rock anchoring problems in the direction of "large, deep and di cult", sudden engineering disasters and major malignant accidents caused by nonlinear large deformation damage have occurred frequently in recent years.…”

Buried Depth of a Submarine Pipeline Based on Anchor Penetration

“…Kim et al proposed a rational analytical embedment model, based on strain rate-dependent shearing resistance and fluid mechanics drag resistance to predict the embedment depth in the field [2]. They also adopted the large deformation finite-element (LDFE) method to analyze the behavior of a torpedo anchor during dynamic installation in two-layered non-homogeneous clay sediments, and proposed an extended total energy-based method to assess the anchor embedment depth in two-layered fine-grained ocean sediments [3]. Wang et al conducted several penetration experiments and proposed a formula calculating the penetration depth in soft wet soil [4].…”