Rates of weathering and temporal changes in strength of bedrock of marine terraces in Boso Peninsula, Japan

Hachinohe, Shoichi; Hiraki, Nobuaki; Suzuki, Takasuke

doi:10.1016/s0165-1250(00)80015-2

Cited by 7 publications

(6 citation statements)

References 5 publications

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“…This assumption represents an oversimplification of reality, since weathering has a greater effect on material close to the exposed surface than on material well within the slope. As a matter of fact, from the scanty experimental data available [ Yokota and Iwamatsu , 2000; Hachinohe et al , 2000], it can be inferred that soil strength varies between the exposed slope forefront, where it is minimal, up to an internal weathering propagation front, to remain constant within inner slope regions (see Figure 2). Unfortunately, such a spatial variation cannot be taken into account easily by an analytical approach, as the limit analysis method requires very complex calculations already for the case of uniform weathering.…”

Section: Behavior Of Geomaterialsmentioning

confidence: 99%

Modeling the evolution of natural cliffs subject to weathering: 1. Limit analysis approach

Utili

Crosta

2011

J. Geophys. Res.

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[1] Retrogressive landsliding evolution of natural slopes subjected to weathering has been modeled by assuming Mohr-Coulomb material behavior and by using an analytical method. The case of weathering-limited slope conditions, with complete erosion of the accumulated debris, has been modeled. The limit analysis upper-bound method is used to study slope instability induced by a homogeneous decrease of material strength in space and time. The only assumption required in the model concerns the degree of weathering within the slope, and for this we assumed and tested different weathering laws. By means of this method, the evolution of cliffs subject to strong weathering conditions (weathering-limited conditions) was predicted. The discrete succession of failures taking place was modeled taking into account the geometry assumed by slopes as a consequence of previous mass movements. The results have been compared with published data from long-term slope monitoring and show a good match between experimental observations and analytical predictions. The retrogressive evolution of the slope occurs with decreasing size of the unstable blocks, following a logarithmic volume-frequency relationship. A nonlinear relationship is found between mass flux and average slope gradient. A set of normalized solutions is presented both by nomograms and tables for different values of slope angle, cohesion, and internal friction angle.Citation: Utili, S., and G. B. Crosta (2011), Modeling the evolution of natural cliffs subject to weathering: 1. Limit analysis approach,

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Section: Behavior Of Geomaterialsmentioning

confidence: 99%

Modeling the evolution of natural cliffs subject to weathering: 1. Limit analysis approach

Utili

Crosta

2011

J. Geophys. Res.

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“…This is a problem in a physical sense in that there is no time lag between the exposure of the rock surface to a new weathering environment and the onset of tafone development. Weathering gradually degrades the surface material causing considerable strength reduction (Mottershead, ; Mottershead and Pye, ; Suzuki and Hachinohe, ; Hachinohe et al , ; Aoki and Matsukura, ), leading to mechanical breakdown in the mode of granular disintegration, blistering, flaking, or scaling, which results in tafone formation. A certain period of time should therefore precede the initiation of tafoni.…”

Section: Introductionmentioning

confidence: 99%

Application of an S‐shaped curve model to the temporal development of tafoni of salt‐weathering origin

Sunamura¹,

Aoki

2011

Earth Surf Processes Landf

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To describe temporal change in tafone development, an S-shaped curve equation is proposed: Z = Z c [1 − (n + 1) exp (− β t ) + n exp (− (1 + 1/n) β t )] , where Z is observed tafone depth, Z c is ultimate tafone depth, t is time, and n and β are constants. The applicability of this model is examined using tafone data selected from seven sites, which are categorized into three different salt-weathering environments: a spray/splash-dominant (occasionally wave-affected) supra-tidal zone, aerosol-affected coastal regions, and inland desert areas. The results indicate that the equation can well describe tafone development in each of these environments. An investigation based on the values of n and β, determined through a best fit of the equation to the data, suggests that n characterizes site-specific environmental conditions and β reflects the magnitude of factors controlling the recession mechanism of tafone surfaces. It is found that (1) the maximum rate of tafone growth dramatically decreases from supra-tidal, through coastal, to desert environments, and (2) the growing mode of tafoni is different depending on the environmental settings. The erosional force to facilitate the development of tafoni at supra-tidal sites is estimated to be about 400 times greater than that in the general coastal area.

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“…A needle-type penetrometer was used for a study on strength reduction of coastal rocks owing to weathering (Suzuki & Hachinohe 1995;Hachinohe et al 1999a, b). They applied it to three cores of sandstone, which were obtained by drilling vertically from the surface of three uplifted coastal terraces with different ages near the tip of the Boso Peninsula, Japan, and Hachinohe et al (1999a) revealed the temporal change in weathering profiles.…”

Section: Discussionmentioning

confidence: 99%

Chapter 12 The rock coast of Japan

Sunamura¹,

Tsujimoto

Aoki

2014

Memoirs

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The Japanese islands, situated in a tectonically unstable region with a highly variable geology, are exposed to high wave energy and microtidal environments in most locations. Rocky coasts are common, most having a steep cliff with coastal recession being primarily driven by wave erosion. A fundamental relationship between recession and wave force is obtained through reanalysis of previous laboratory data. On the basis of this relation a model is constructed for the development of type B platforms, that is, horizontal or subhorizontal platforms that have a steep scarp at the seaward edge. The process of wave attenuation on this type of platform and weathering-induced strength reduction of rocks are incorporated into the model. The model is applied to the southwestern coast of the Kii Peninsula and a platform at Ebisu-jima of the Izu Peninsula. Long-term development rates of platforms in the former area are examined: the model indicates that the rate of erosion when platforms were initiated at 6000 years BP is two orders of magnitude greater than present. At the Ebisu-jima platform, wave-induced erosion processes are explored on a daily basis: the model provides a description of temporal variations in platform growth, although the result is not fully satisfactory.Gold Open Access: This article is published under the terms of the CC-BY 3.0 license.

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Rates of weathering and temporal changes in strength of bedrock of marine terraces in Boso Peninsula, Japan

Cited by 7 publications

References 5 publications

Modeling the evolution of natural cliffs subject to weathering: 1. Limit analysis approach

Modeling the evolution of natural cliffs subject to weathering: 1. Limit analysis approach

Application of an S‐shaped curve model to the temporal development of tafoni of salt‐weathering origin

Chapter 12 The rock coast of Japan

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