Slaking is a mechanical–hydraulic process in which geomaterials disintegrate or crumble when subjected to wetting and drying cycles; mudstone is particularly susceptible to this process. This paper explores the slaking behaviour of geomaterials derived from several kinds of mudstone and the mechanical consequences using a comprehensive set of experimental data obtained through accelerated slaking tests and newly developed one-dimensional compression slaking tests. These data confirm that slaking in crushed mudstone is accompanied by a variation in the particle size distribution during wetting and drying cycles, and a variation in grading results in an irreversible change in mechanical characteristics, such as the reference packing density. Significant compression is also found to occur without any change in effective confining stress. The results of X-ray fluorescence analysis, X-ray diffraction analysis and scanning electron microscopy are also used to elucidate the effects of mineralogy and particle texture on the slaking characteristics of crushed mudstone. Finally, it is also mentioned that constitutive modelling can take slaking into consideration by describing the evolution of an appropriate grading index due to slaking, and then linking this to reference packing density.
Shallow and deep seated landslides in natural slopes are often induced by rainfall. The cause of the failure is usually considered to be due to the decrease in effective confining stress due to a suction loss by water infiltration. However, rainwater infiltrates into the slope surface resulting in a reduction of shear strength of soil and deformation and failure may occur even without significant change in effective stress. It is thus essential to examine the deformation and failure characteristics of the soil induced by wetting. This study investigates on the wetting-induced deformations under isotropic compression condition and triaxial shearing condition using a triaxial test apparatus for unsaturated soils. Two soil samples collected from the active landslide sites from Pakistan were used to examine both the shear strength and deformation behavior during water infiltration at different levels of deviatoric stress by keeping the deviatoric stress constant during the water infiltration stage.The test results showed that, even though the deviatoric stress is kept constant during water permeation at different stress levels, the distortional deformation was exhibited due to wetting by a significant amount for both samples. The effect of water infiltration on the deformation behavior of unsaturated soil regarding the change in the degree of saturation and void ratio was also observed. There was a decrease in the void ratio for both specimens during increasing the degree of saturation at different level of deviatoric stress ratio. Under higher deviator stress, more decrease in void ratio and an increase of the degree of saturation were observed.Therefore, it can be said that deformation of soil due to water infiltration is a critical phenomenon and it should be considered while analyzing the soil behavior due to water infiltration by rainfall or rise in groundwater level, even if the slope is not failed, significant deformations may hinder the performance of natural slopes.
Batuan sedimen khususnya batu lempung sampai saat ini belum banyak digunakan dalam dunia konstruksi sebagai pondasi dan material konstruksi terutama bangunan jalan, dan cenderung memiliki kualitas yang rendah karena kemampuan batu lempung yang jelek sebagai material konstruksi dan memiliki potensi deformasi yang sangat besar. Penelitian ini dilakukan untuk mengetahui pengaruh fenomena slaking yang meme-ngaruhi deformasi pada batu lempung. Batu lempung yang terbentuk dari rombakan batu lainnya mengalami kompaksi dan suhu yang tinggi sehingga material tersebut menjadi padat, dan memiliki pori yang sangat kecil akibat keseragaman partikelnya. Pengujian yang dilakukan adalah analisa X-Ray Diffraction, Accelerated Slaking Test, serta One Dimensional Compression Test. Diketahui bahwa jenis mineral yang menyusun batuan Daerah Lemong berupa Dolomite, Boron Nitride, 3-Nitro-nitromethyl-1 H-1,2,4-triazole, dan Praseodymium. Berdasarkan hasil uji XRD tersebut dapat diketahui rata-rata penyusun batuan yang dijadikan sampel tersusun oleh mineral Kapur (dolomite), memiliki tekstur yang keras ketika padat. Berdasarkan penelitian ini menunjukkan bahwa jenis batu lempung Lemong mengalami deformasi yang sangat kecil, karena dipengaruhi adanya ukuran pori-pori butiran dalam partikel yang sangat kecil, sehingga peneliti mendapatkan solusi untuk mengetahui tingkat kemampuan batu lempung Lemong layak dijadikan material konstruksi.
Geotechnical issues such as differential settlements have been reported usually in embankments made of materials derived from weak rocks such as mudstones, siltstones, and shales. The primary cause of the issue is a gradual weakening due to weathering. Crushed weak rocks tend to turn into smaller particles under repeated wetting and drying processes. This phenomenon is a mechanical-hydraulic process known as “slaking”. The present paper discusses the deformation of crushed weak rocks due to slaking and its countermeasure. We performed a series of one-dimensional slaking tests on several weak rocks. We first performed one-dimensional compression tests on dried samples, and applied wetting and drying cycles to the samples while keeping the compression stress constant. The test results revealed that particle size distribution of the samples was broadened due to cyclic wetting and drying processes and that significant compression was exhibited. Moreover, we explored possible countermeasures for reducing the slaking-induced deformation and revealed that compacting the soil to a denser state is the most effective way in reducing the slaking-induced deformation of the crushed mudstone.
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