scholarly journals Flow liquefaction potential of loose sand: stress path envelope and energy–based evaluation

2020 ◽  
Author(s):  
Kun Pan ◽  
Zhongxuan Yang ◽  
Yuanqiang Cai
Keyword(s):  
Axial Strain ◽  
Stress Path ◽  
Dissipated Energy ◽  
Loose Sand ◽  
Liquefaction Potential ◽  
Cyclic Shear ◽  
Cyclic Resistance ◽  
Potential Applicability ◽  
Potential Evaluation ◽  
Flow Liquefaction

Flow liquefaction, which is characterized by sudden collapse following the unstable behavior of saturated loose sand, may lead to the most catastrophic consequence of all liquefaction–related phenomena. This note presents a systematic experimental investigation into the flow liquefaction potential of sand under various initial and cyclic shear conditions. The cyclic flow liquefaction responses are compared to the monotonic shear results under an identical initial testing condition. It is found that the effective stress path of a monotonic test appears to envelop that of its corresponding cyclic test. The energy–based liquefaction potential evaluation indicates that the accumulative dissipated energy is uniquely correlated not only with the pore pressure and axial strain induced in sand, but also with the degraded stiffness during cyclic loading. Furthermore, the energy capacity for triggering the flow liquefaction appears to be intimately related to the cyclic resistance of sand; this signifies the potential applicability of energy–based liquefaction potential evaluation using strength data available in conventional analysis.

scholarly journals Undrained Cyclic Response and Resistance of Saturated Calcareous Sand considering Initial Static Shear Effect

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Baojian Li ◽  
Panpan Guo ◽  
Gaoyun Zhou ◽  
Zhe Wang ◽  
Gang Lei ◽  
...  
Keyword(s):  
Shear Stress ◽  
Relative Density ◽  
Shear Stresses ◽  
Loose Sand ◽  
Calcareous Sand ◽  
Cyclic Shear ◽  
Cyclic Response ◽  
Dense Sand ◽  
Cyclic Resistance ◽  
Static Shear

Sand elements in the natural or manmade field have often undergone initial static shear stresses before suffering cyclic loading. To explore the effect of static shear stress, a series of undrained cyclic triaxial tests were performed on dense and loose calcareous sand under different initial and cyclic shear stresses. The triaxial test results are used to describe the effect of static shear stress on the cyclic response of the calcareous sand with different relative density. Cyclic mobility, flow deformation, and residual deformation accumulation are the three main failure modes under varying static and cyclic shear stress levels. The cyclic resistance of dense sand is greater than that of loose sand, but the initial static stress has different effects on the cyclic resistance of the two kinds of sand. The dense sand owns a higher cyclic resistance with SSR increasing, while for the loose sand, 0.12 is the critical SSR corresponding to the lowest value of the cyclic resistance. The dense sand has more fast accumulation of dissipated energy, compared with loose sand. Additionally, an exponential relationship is established between static shear stress, relative density, and normalized energy density.

scholarly journals Analisis Potensi Likuifaksi dengan Metode Deterministik di Wilayah Surabaya

2019 ◽  
Vol 4 (1) ◽  
pp. 68
Author(s):  
Himatul Farichah ◽  
Putu Tantri Kumala Sari
Keyword(s):  
Relative Density ◽  
Degree Of Saturation ◽  
Fine Content ◽  
Alluvial Deposits ◽  
Liquefaction Potential ◽  
Cyclic Shear ◽  
Potential Analysis ◽  
Cyclic Resistance ◽  
Advanced Analysis ◽  
Earthquake Potential

Surabaya has an earthquake potential reach to 6.5 Mw. Moreover, on average, Surabaya area is a lowland which is alluvial deposits. Thus, it is required to perform potential liquefaction. Liquefaction potential analysis was performed by taking the soil data from the center of Surabaya. The initial of liquefaction potential analysis was conducted by considering soil gradation, relative density (DR), fine content (FC), degree of saturation (SR) dan SPT number. However, the advanced analysis was undertaken by utilizing Youd and Idriss 2001 dan metode Idriss 2008. The results of initial of liquefaction potential analysis show that the soil has potential to be liquefied at the depth 1-7m, however at the depth 22m the soil is not liquefied. Furthermore, the results of advanced analysis and conclusions of the analysis show that the soil has a liquefied potential at the depth 17 m from the surfaceABSTRAK Kota Surabaya memiliki potensi gempa yang terjadi bisa mencapai 6.5 Mw. Selain itu, Wilayah kota Surabaya merupakan daerah yang rata-rata dataran rendah, yang berkisar 80% merupakan endapan alluvial. Sehingga perlu dilakukan analisis potensi likuifaksi. Analisis potensi likuifaksi hanya dilakukan pada data tanah wilayah Surabaya Pusat. Analisis awal potensi likuifaksi dilakukan berdasarkan aspek gradasi tanah, relative density (DR), fine content (FC), derajat kejenuhan (SR), dan jumlah pukulan SPT. Sedangkan analisis lanjutan dengan menghitung Cyclic Shear Ratio (CSR), Cyclic Resistance Ratio (CRR), dan Factor of safety (FS) dengan menggunakan metode Youd dan Idriss 2001 dan metode Idriss 2008. Berdasarkan analisis awal, pada kedalaman 1-7 m masih ada potensi likuifaksi, sedangkan tidak ada lagi potensi likuifaksi pada kedalaman lebih dari 22 m. Berdasarkan analisis lanjutan dan kesimpulan analisis, hampir semua kedalaman memiliki potensi likuifaksi hingga kedalaman 17m.Kata kunci : Likuifaksi; gempa; analisis potensi likuifaksi

scholarly journals Effect of Anisotropic Yielding on the Flow Liquefaction of Loose Sand

2002 ◽  
Vol 42 (3) ◽  
pp. 33-44 ◽  
Author(s):  
S.M. Reza Imam ◽  
Dave H. Chan ◽  
Peter K. Robertson ◽  
Norbert R. Morgenstern
Keyword(s):  
Loose Sand ◽  
Anisotropic Yielding ◽  
Flow Liquefaction

scholarly journals Evaluation of liquefaction potentials based on shear wave velocities in Pohang City, South Korea

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Yumin Ji ◽  
Byungmin Kim ◽  
Kiseog Kim
Keyword(s):  
South Korea ◽  
Shear Wave ◽  
Wave Velocity ◽  
Shear Wave Velocity ◽  
Ground Surface ◽  
Velocity Profiles ◽  
Liquefaction Potential ◽  
Attenuation Relationships ◽  
Cyclic Resistance ◽  
Sand Boils

AbstractThis study evaluates the potentials of liquefaction caused by the 2017 moment magnitude 5.4 earthquake in Pohang City, South Korea. We obtain shear wave velocity profiles measured by suspension PS logging tests at the five sites near the epicenter. We also perform downhole tests at three of the five sites. Among the five sites, the surface manifestations (i.e., sand boils) were observed at the three sites, and not at the other two sites. The maximum accelerations on the ground surface at the five sites are estimated using the Next Generation Attenuation relationships for Western United State ground motion prediction equations. The shear wave velocity profiles from the two tests are slightly different, resulting in varying cyclic resistance ratios, factors of safety against liquefaction, and liquefaction potential indices. Nevertheless, we found that both test approaches can be used to evaluate liquefaction potentials. The liquefaction potential indices at the liquefied sites are approximately 1.5–13.9, whereas those at the non-liquefied sites are approximately 0–0.3.

scholarly journals Effect of Variable Confining Pressure on Cyclic Triaxial Behavior of K0-consolidated Soft Marine Clay

2018 ◽  
Vol 4 (4) ◽  
pp. 755
Author(s):  
Lei Sun
Keyword(s):  
Pore Water ◽  
Pore Water Pressure ◽  
Axial Strain ◽  
Water Pressure ◽  
Confining Pressure ◽  
Stress Path ◽  
Cyclic Stress ◽  
Marine Clay ◽  
Stress Ratios ◽  
Variable Confining Pressure

The effect of variable confining pressure (VCP) on the cyclic deformation and cyclic pore water pressure in K0-consolidated saturated soft marine clay were investigated with the help of the cyclic stress-controlled advanced dynamic triaxial test in undrained condition. The testing program encompassed three cyclic deviator stress ratios, CSR=0.189, 0.284 and 0.379 and three stress path inclinations ηampl=3,1 and 0.64. All tests with constant confining pressure (CCP) and variable confining pressure (VCP) have identical initial stress and average stress. The results were analyzed in terms of the accumulative normalized excess pore water pressure rqu recorded at the end of each stress cycle and permanent axial strain, as well as resilient modulus. Limited data suggest that these behavior are significantly affected by both of the VCP and CSR. For a given value of VCP, both of the pore water pressure rqu and permanent axial strains are consistently increase with the increasing values of CSR. However, for a given value of CSR, the extent of the influence of VCP and the trend is substantially depend on the CSR.

scholarly journals Standard Penetration Tests and Soil Liquefaction Potential Evaluation

1980 ◽  
Vol 20 (4) ◽  
pp. 95-111 ◽  
Author(s):  
Fumio Tatsuoka ◽  
Toshio Iwasaki ◽  
Ken-Ichi Tokida ◽  
Susumu Yasuda ◽  
Makoto Hirose ◽  
...  
Keyword(s):  
Soil Liquefaction ◽  
Liquefaction Potential ◽  
Potential Evaluation ◽  
Penetration Tests

Mechanical Characteristics of Ningbo Marine Deposit Soft Clay under Different Stress Paths

2011 ◽  
Vol 250-253 ◽  
pp. 2093-2097
Author(s):  
Chen Bin ◽  
Jun Neng Ye ◽  
Gan Bin Liu
Keyword(s):  
Effective Stress ◽  
Mechanical Characteristics ◽  
Axial Strain ◽  
Soft Clay ◽  
Stress Path ◽  
Shear Mode ◽  
Test Results ◽  
Total Stress ◽  
Consolidation Pressure ◽  
Marine Deposit

Based on a series of consolidated-undrained stress path tests, the mechanical characteristics of Ningbo marine deposit soft clay under K0 consolidation condition are systematically studied for different consolidation pressure, i.e.,60, 120 and 200kPa, in the GDS stress path triaxial system. Three kinds of stress path, i.e., DE (increase p), DG(constant p) and DF(reduce p), are carried out, and the characteristics of stress-axial strain relation, stress path and strength under different stress paths are compared. The test results show that the effective stress paths under consolidated-undrained shear are mainly related to initial consolidation, and the controlled shear mode has evident effect on the effective stress paths. In addition, the stress path has a certain influence on both the total stress and the effect stress strength.

Laboratory evaluation of K0 for overconsolidated clays

1991 ◽  
Vol 28 (5) ◽  
pp. 650-659 ◽  
Author(s):  
Vinod K. Garga ◽  
Mahbubul A. Khan
Keyword(s):  
Axial Stress ◽  
Axial Strain ◽  
Stress Path ◽  
Horizontal Stress ◽  
In Situ Stress ◽  
Laboratory Method ◽  
Laboratory Evaluation ◽  
Triaxial Apparatus ◽  
Overconsolidated Clays

Most of the laboratory testing methods available for the evaluation of in situ horizontal stresses are applicable to normally consolidated or lightly overconsolidated clays. This paper describes a new laboratory method for the determination of in situ horizontal stresses of heavily overconsolidated clays using a stress-path triaxial apparatus. The proposed method is based on the concept that if the radial stress exceeds the in situ horizontal stress, while maintaining the axial stress constant and equal to the in situ vertical effective stress, only then will the sample experience significant axial strain. The results obtained for undisturbed samples of an overconsolidated clay crust are found to be in agreement with some available methods. For verification of the applicability of the proposed method, K0 was determined for artificially prepared samples that had been subjected to known stress paths simulating field stress history. Key words: K0, overconsolidation, in situ stress, in situ test, clay crust, laboratory test.

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