scholarly journals TINJAUAN RINGKAS BERBAGAI TEKNIK TERKINI UNTUK MENENTUKAN KUAT GESEK EROSIF TANAH

2019 ◽  
Vol 18 (1) ◽  
Author(s):  
Tommy Ekamitra Sutarto
Keyword(s):  
Shear Strength ◽  
Bank Erosion ◽  
Short Review ◽  
Soil Mass ◽  
Soil Parameters ◽  
Fluvial Erosion ◽  
Stream Bank ◽  
Erodibility Coefficient ◽  
Hydrodynamic Shear ◽  
Mass Failure

ABSTRACTStream bank erosion manifests in two main modes, namely mass failure and fluvial erosion. Fluvial erosion is a quasi-continuous entrainment of individual soil grains or grain flocs or chunks from the bank face due to the hydrodynamic shear flow action. It occurs under water with retreat lengths in millimeter or centimeter scale. The interaction between fluvial erosion and mass failure determines the shape and retreat rate of the stream bank (Rinaldi et al., 2008). It is not rare, fluvial erosion which occurs at the bank toe later triggers slumping of soil mass known as mass failure. Despite its importance, the mechanism of fluvial erosion is less understood. This is predominantly due to lack of technique for measuring two key bank soil parameters that determine fluvial erosion rate, e.g., erosion shear strength τcand the erodibility coefficient M (Papanicolaou et al., 2007, Grabowski et al., 2011, Sutarto et al., 2014a). The goal of this manuscript is to provide a short review on the various techniques for measuring τcand M proposed and applied in various studies. The advantages and the limitations of each technique are discussed to get a glimpse on where we stand and what challenge remains to overcome.Key words : Fluvial erosion, erosion shear strength, erodibility coefficientABSTRAKErosi tebing sungai terjadi dalam dua model utama, yakni erosi gerusan dan longsor atau keruntuhan. Erosi gerusan ditandai dengan tergerusnya butiran atau bongkahan tanah, secara hampir kontinu, dari permukaan tebing akibat daya gerus air sungai. Erosi gerusan berlangsung di bawah muka air dan magnitudo erosi sangat kecil dalam skala millimeter hingga centimeter saja. Interaksi antara erosi gerusan dan longsor membentuk profil permukaan tebing sungai dan mendikte laju pergerakan mundur tebing sungai (Rinaldi dkk., 2008). Tidak jarang erosi gerusan, yang umumnya lebih dominan terjadi di tumit tebing, memicu longsor tebing. Meskipun demikian pentingnya peran erosi gerusan, pemahaman tentang mekanisme erosi gerusan tidak sebaik pemahaman tentang longsor tebing. Hal ini disebabkan belum adanya metode akurat yang disepakati bersama untuk mengukur dua parameter kunci tanah yang menentukan laju erosi gerusan, yakni kuat gesek erosif τcdan koefisien erodibilitas M (Papanicolaou dkk., 2007, Grabowski dkk., 2011, Sutarto dkk., 2014a). Artikel ini memaparkan hasil tinjauan ringkas tentang teknik pengukuran parameter τcdan M yang ditawarkan dan sudah diaplikasikan dalam berbagai studi. Kelebihan dan kekurangan dari masing-masing teknik juga akan dibahas untuk memahami sejauh mana kemajuan yang telah dicapai dan permasalahan yang masih harus diatasi.Kata kunci : Erosi gerusan, kuat gesek erosif, koefisien erodibilitas

Finite Element Modeling of a Mechanically Stabilized Earth Trial Wall

2021 ◽  
pp. 036119812110164
Author(s):  
Andrew Lees ◽  
Michael Dobie
Keyword(s):  
Finite Element ◽  
Shear Strength ◽  
Retaining Wall ◽  
Back Analysis ◽  
Soil Parameters ◽  
Failure Behavior ◽  
Valuable Insight ◽  
Deformation And Failure ◽  
First Case ◽  
Soil Shear Strength

Polymer geogrid reinforced soil retaining walls have become commonplace, with routine design generally carried out by limiting equilibrium methods. Finite element analysis (FEA) is becoming more widely used to assess the likely deformation behavior of these structures, although in many cases such analyses over-predict deformation compared with monitored structures. Back-analysis of unit tests and instrumented walls improves the techniques and models used in FEA to represent the soil fill, reinforcement and composite behavior caused by the stabilization effect of the geogrid apertures on the soil particles. This composite behavior is most representatively modeled as enhanced soil shear strength. The back-analysis of two test cases provides valuable insight into the benefits of this approach. In the first case, a unit cell was set up such that one side could yield thereby reaching the active earth pressure state. Using FEA a test without geogrid was modeled to help establish appropriate soil parameters. These parameters were then used to back-analyze a test with geogrid present. Simply using the tensile properties of the geogrid over-predicted the yield pressure but using an enhanced soil shear strength gave a satisfactory comparison with the measured result. In the second case a trial retaining wall was back-analyzed to investigate both deformation and failure, the failure induced by cutting the geogrid after construction using heated wires. The closest fit to the actual deformation and failure behavior was provided by using enhanced fill shear strength.

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.

Bank Stability Analysis for Fluvial Erosion and Mass Failure

2014 ◽  
Author(s):  
A. N. Thanos Papanicolaou ◽  
Tommy Sutarto ◽  
Christopher G. Wilson ◽  
Eddy J. Langendoen
Keyword(s):  
Stability Analysis ◽  
Bank Stability ◽  
Fluvial Erosion ◽  
Mass Failure

Mobile Packaging and Interconnect Trends

2014 ◽  
Vol 2014 (DPC) ◽  
pp. 1-21
Author(s):  
Brandon Prior
Keyword(s):  
Shear Strength ◽  
High Temperature ◽  
Thick Film ◽  
Cross Sections ◽  
Shear Test ◽  
Short Review ◽  
Test Machine ◽  
Die Attach ◽  
Shear Failures ◽  
Film Substrate

This paper will focus on emerging and fast growth package solutions to meet mobile products' density and cost requirements. A short review of where package miniaturization and modularization has taken us so far, and where it will lead in the next 5 years. Teardowns of high density systems and packages will be used to illustrate key points. Low temperature Ag sintering technology provides a lead-free die attachment compatible with high temperature (300°C) applications. Previous work with Ag sintering has required some pressure during the sintering process or been limited to small area die. In this paper, a pressureless sintering of micro-scale silver paste procedure is presented for large (8mm x 8mm) area die. Experimental combinations included: Ag metallized Si die, Au metallized Si die, Ag thick film substrate metallization, Au thick film substrate metallization, PdAg thick film metallization and sintering temperature. For Au metallization (die and/or substrate), the initial shear strength results were good with 8mm x 8mm die sintered at lower temperatures (200°C). The shear strength was out range of our shear test machine (100 kg), corresponding to >15.3 MPa. However, after aging for 24 hours at 300°C, the shear strength dropped significantly to 40.38 Kg (6.183 MPa). An SEM was used to characterize cross sections of as-built and aged sample. The decrease in die shear strength with high temperature sintering (250°C and 300°C) or high temperature aging is attributed to surface diffusion of Ag along the Au surface resulting in a dense Ag layer adjacent to the Au surface and a depletion layer within the die attach on the opposite side of the the dense Ag layer. Shear failures occurred through the depleted region. For Ag metallization, no decrease in shear strength was observed with 300°C aging. Shear strength of 8x8cm2 dies was out range of our shear test machine (>100 kg, >15.3 MPa) as-built. The shear strength remained out of range (>15.3MPa) after more than 2000 hours of 300C aging.

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