Barodesy with a new concept for critical void ratio

geotechnik ◽  
2021 ◽  
Author(s):  
Dimitrios Kolymbas
Keyword(s):  
Void Ratio ◽  
Critical Void

Rain impact soil crust. IV. Packing of sand and silt fractions by raindrops

Soil Research ◽  
1991 ◽  
Vol 29 (2) ◽  
pp. 331 ◽  
Author(s):  
AJ Moss
Keyword(s):  
Void Ratio ◽  
Packed Bed ◽  
Stress Waves ◽  
Soil Crust ◽  
Structural Element ◽  
Loose Packing ◽  
Impact Events ◽  
Underlying Soil ◽  
Silt Layer ◽  
Critical Void

Comparison of resistance to fast and slow deformation by rain-packed and artificially prepared sand and silt fractions showed that, whereas sands are left in loosely packed states after accrual under rain impact, silts are left more densely packed, i.e. below critical void ratio. This contrast is attributed mainly to the declining importance of hydraulic penetration with pore size. Rain-packed silt is dilatant and cannot deform without expansion which, in turn, requires water entry at a rate compatible with the required deformation. In the short duration of rain-impact events, hydrodynamic time lagging occurs because water can move only slowly through the small silt pores. Consequently, densely packed silt remains essentially rigid. However, drop-outflow sheets are able to entrain silt and distribute it over the surface as densely packed bed-load deposits, thus maintaining its dilatancy. Sand, its larger pores invaded by hydraulic penetration jets which maintain loose packing, cannot behave in this manner. Relative stability of the silt layer on soil surfaces, and its suppression of hydraulic penetration, allow transmission of drop-generated stress waves which cause the immediately underlying soil to become compacted into the main structural element of the rain-impact soil crust.

Concept of critical void ratio used in estimating dynamic stability of sands

2009 ◽  
Vol 64 (2) ◽  
pp. 116-122
Author(s):  
E. S. Kushnareva ◽  
E. A. Voznesensky
Keyword(s):  
Dynamic Stability ◽  
Void Ratio ◽  
Critical Void

scholarly journals KARAKTERISTIK ENDAPAN SEDIMEN PANTAI TERHADAP PENGARUH LIQUIFAKSI DI KAWASAN PESISIR PANGANDARAN DAN SEKITARNYA, KABUPATEN CIAMIS, JAWA BARAT

2016 ◽  
Vol 6 (3) ◽  
Author(s):  
Kris Budiono ◽  
Purnomo Raharjo
Keyword(s):  
Void Ratio ◽  
Ground Surface ◽  
Soil Mechanic ◽  
Geological Hazards ◽  
Survey Area ◽  
Ground Acceleration ◽  
Richter Scale ◽  
Simplified Procedure ◽  
Sand And Gravel ◽  
Critical Void

Liquifaksi adalah salah satu bencana geologi yang berhubungan dengan kegempaan, dimana tekanan pori dalam tanah atau sedimen mengalami peningkatan akibat getaran, sehingga mengakibatkan aliran air ke arah permukaan tanah. Liquifaksi umumnya terjadi pada dataran rendah termasuk kawasan pesisir. Daerah penelitian yang terletak di sekitar pantai Pangandaran dan Parigi terdiri dari endapan lempung, lanau, pasir dan kerikil yang bersifat lepas dan jenuh air, secara regional sering dipengaruhi oleh kekuatan gempa antara 5,5 – 6 skala Richter dengan percepatan tanah antara 150 – 200 mgal. Kondisi seperti ini apabila terjadi gempa sangat memungkinkan untuk terjadi liquifaksi. Berdasarkan hasil perhitungan secara kuantitatif nisbah pori kritis, tidak semua lokasi penelitian akan mengalami liquifaksi pada percepatan permukaan 150 – 200 mgal. Berdasarkan nilai tumbukan SPT yang dipakai untuk analisis “simplified procedure”, daerah penelitian secara umum relatif kecil terhadap bahaya liquifaksi. Namun demikian berdasarkan korelasi antara sifat mekanik tanah dengan nilai SPT, pada kedalaman 0 – 8 m terdapat lapisan sedimen yang cukup rentan terhadap liquifaksi. Kata kunci: Liquifaksi,sedimen pantai,Pangandaran Liquefaction is one of many geological hazards related to an earthquake, where the void ratio pressure in soil or sediment will increase due to the vibration, that causing water flow up to the ground surface. Generally liquefaction is occurred in the low lying areas including coastal zone. The survey area located in the Pangandaran and Parigi coasts, is consisted of clay, silt, sand and gravel, of loose and saturated properties, generally is frequently influenced by 5,5 – 6 Richter scale of earthquake strength with the ground acceleration between 150 – 200 mgal. The liquefaction will be occurred in this condition if there is an earthquake. Based on the quantitatively calculation of critical void ratio, the liquefaction at ground acceleration of 150 – 200 mgal will not be occurred at all of the survey area. Based on the number of blows of SPT which is used for simplified procedure analysis, it shows that the study area is less influenced by the liquefaction. Nevertheless , based on the correlation between soil mechanic properties and SPT value, there is potential liquefiable sediments layer between the depth of 0 – 8 meters. Key words: liquefaction, coastal sediment, Pangandaran

Simple Shear in Granular Media

1997 ◽  
Vol 50 (11S) ◽  
pp. S81-S86 ◽  
Author(s):  
Robert M. Haythornthwaite
Keyword(s):  
Principal Stress ◽  
Simple Shear ◽  
Granular Media ◽  
Void Ratio ◽  
Test Chamber ◽  
Outer Wall ◽  
Intermediate Principal Stress ◽  
Angle Of Internal Friction ◽  
Shear Box ◽  
Critical Void

The ring shear box is analyzed using an isotropic strain hardening/softening model for granular media, permitting an estimate to be made of the stresses developed under conditions of simple shear, at the critical void ratio. Observation of the radial stress on the inner or outer walls of the test chamber would provide a measure of the relative value of the otherwise unknown intermediate principal stress. In a series of five tests on a quartz sand, average pressures exerted by the sand on the outer wall of the test chamber reached well defined, repeatable levels. As interpreted by the theory, the tests showed that the intermediate principal stress was equal to the direct stress on the Coulomb friction planes during simple shear: (1−sinφcv)σ1=σ2=(1+sinφcv)σ3 where σ1 > σ2 > σ3 (compression positive), and φcv is the angle of internal friction at the critical void ratio, ie, during continuing displacement at constant volume. Similar observations are impossible for plane strain in general because displacement cannot be controlled so completely, but it is reasonable to conjecture that the same relationship holds for all such deformations, including those associated with the active and passive Rankine states.

scholarly journals Mechanical Properties and Micro Mechanism of Nano-Clay-Modified Soil Cement Reinforced by Recycled Sand

2021 ◽  
Vol 13 (14) ◽  
pp. 7758
Author(s):  
Biao Qian ◽  
Wenjie Yu ◽  
Beifeng Lv ◽  
Haibo Kang ◽  
Longxin Shu ◽  
...  
Keyword(s):  
Shear Strength ◽  
Void Ratio ◽  
Soil Mass ◽  
Direct Shear ◽  
Test Results ◽  
The Sustainable Development ◽  
Direct Shear Tests ◽  
Soil Cement ◽  
Nano Clay ◽  
New Material

To observe the effect of recycled sand and nano-clay on the improvement of the early strength of soil-cement (7d), 0%, 10%, 15% and 20% recycled sand were added. While maintaining a fixed moisture content of 30%, the ratios of each material are specified in terms of soil mass percentage. The shear strength of CSR (recycled sand blended soil-cement) was investigated by direct shear test and four groups of specimens (CSR-1, CSR-2, CSR-3 and CSR-4) were obtained. In addition, 8% nano-clay was added to four CSR groups to obtain the four groups of CSRN-1, CSRN-2, CSRN-3 and CSRN-4 (soil-cement mixed with recycled sand and nano-clay), which were also subjected to direct shear tests. A detailed analysis of the modification mechanism of soil-cement by recycled sand and nano-clay was carried out in combination with scanning electron microscopy (SEM) and IPP (ImagePro-Plus) software. The test results showed that: (1) CSR-3 has the highest shear strength due to the “concrete-like” effect of the incorporation of recycled sand. With the addition of 8% nano-clay, the overall shear strength of the cement was improved, with CSRN-2 having the best shear strength, thanks to the filling effect of the nano-clay and its high volcanic ash content. (2) When recycled sand and nano-clay were added to soil-cement, the improvement in shear strength was manifested in a more reasonable macroscopic internal structure distribution of soil-cement. (3) SEM test results showed that the shear strength was negatively correlated with the void ratio of its microstructure. The smaller the void ratio, the greater the shear strength. This shows that the use of reclaimed sand can improve the sustainable development of the environment, and at the same time, the new material of nano-clay has potential application value.

scholarly journals Experimental Study on Improvement of Marine Soft Soil with Alkali Residue

2018 ◽  
Vol 53 ◽  
pp. 04021
Author(s):  
SHAO Yong ◽  
LIU Xiao-li ◽  
ZHU Jin-jun
Keyword(s):  
Experimental Study ◽  
Compressive Strength ◽  
Unconfined Compressive Strength ◽  
Void Ratio ◽  
Soft Soil ◽  
Compressive Modulus ◽  
Engineering Properties ◽  
Test Results ◽  
Use Of Resources ◽  
One Year

Industrial alkali slag is the discharge waste in the process of alkali production. About one million tons of alkali slag is discharged in China in one year. It is a burden on the environment, whether it is directly stacked or discharged into the sea. If we can realize the use of resources, it is a multi-pronged move, so alkali slag is used to improve solidified marine soft soil in this paper. The test results show that the alkali residue can effectively improve the engineering properties of marine soft soil. Among them, the unconfined compressive strength and compressive modulus are increased by about 10 times, and the void ratio and plasticity index can all reach the level of general clay. It shows that alkali slag has the potential to improve marine soft soil and can be popularized in engineering.

Predicting the saturated hydraulic conductivity of sand and gravel using effective diameter and void ratio

2004 ◽  
Vol 41 (5) ◽  
pp. 787-795 ◽  
Author(s):  
Robert P Chapuis
Keyword(s):  
Hydraulic Conductivity ◽  
Void Ratio ◽  
Saturated Hydraulic Conductivity ◽  
Effective Diameter ◽  
Predictive Capacity ◽  
K Value ◽  
Maximum Value ◽  
New Equation ◽  
Silty Soils ◽  
Sand And Gravel

This paper assesses methods to predict the saturated hydraulic conductivity, k, of clean sand and gravel. Currently, in engineering, the most widely used predictive methods are those of Hazen and the Naval Facilities Engineering Command (NAVFAC). This paper shows how the Hazen equation, which is valid only for loose packing when the porosity, n, is close to its maximum value, can be extended to any value of n the soil can take when its maximum value of n is known. The resulting extended Hazen equation is compared with the single equation that summarizes the NAVFAC chart. The predictive capacity of the two equations is assessed using published laboratory data for homogenized sand and gravel specimens, with an effective diameter d10 between 0.13 and 1.98 mm and a void ratio e between 0.4 and 1.5. A new equation is proposed, based on a best fit equation in a graph of the logarithm of measured k versus the logarithm of d102e3/(1 + e). The distribution curves of the differences “log(measured k) – log(predicted k)” have mean values of –0.07, –0.21, and 0.00 for the extended Hazen, NAVFAC, and new equations, respectively, with standard deviations of 0.23, 0.36, and 0.10, respectively. Using the values of d10 and e, the new equation predicts a k value usually between 0.5 and 2.0 times the measured k value for the considered data. It is shown that the predictive capacity of this new equation may be extended to natural nonplastic silty soils, but not to crushed soils or plastic silty soils. The paper discusses several factors affecting the inaccuracy of predictions and laboratory test results.Key words: permeability, sand, prediction, porosity, gradation curve.

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