CPT - DR - D50 correlations of sands for liquefaction potential analysis

Liquefaction assessment is the main stage in determining the potential liquefaction in a certain site. In order to assess the potential liquefaction, the values of physical and mechanical properties of the soil are very important. Two main parameters that are essentially needed to determine the liquefaction potential in a sand deposit; those are relative density and men particle size. In Indonesia, CPT is a testing method that is very practically famous and often conducted in the field. Assessment of Liquefaction Potential will be cheap and valuable by using the results of the CPT test. For this reason, this paper describes the results of conducted research to obtain the values of the relative density and mean particle size based on the outcomes of the CPT test: those are cone resistance (qc) and friction ration (Rf). The relationship between qc-Rf and Dr-D50 is accelerated by conducting a series of tests on soil samples with variations in the value of relative density and average particle size. The test results are plotted in a graph as well as in the terms of mathematical formulations to figure out for the relationship between CPT values and Dr-D50 in detail for sands. This research is very useful to assess the liquefaction potential in a particular area with very satisfying results

Determination of the Engineering Properties of Submarine Soil Layers in the Bohai Sea Using the Piezocone Penetration Test

Due to the complexity of marine geotechnical engineering, the harsh operating environments, loose subsea soils, and high water contents, it is extremely difficult to obtain soil samples while maintaining the in situ conditions in offshore areas. The engineering properties of submarine soil layers in the Bohai Sea, China, were investigated in this work. The Wison-APB borehole wireline piezocone penetration test (CPTU) system was used to conduct direct measurements of the cone tip resistance, sleeve friction, and pore pressure. The soil classification and the related soil properties, such as the undrained shear strength, sensitivity and overconsolidation ratio, shear strength profile at the investigation depths, and the single pile foundation bearing capacity, were estimated. Laboratory tests were also conducted in this work. The CPT test results show that there were large differences between the results of the CPT tests (Su) and the laboratory experimental results, which may be due to the compact silt and hard clay interbeds in some layers. The soil classification was determined according to the previous literature. The laboratory test results of the undrained shear strength, clay sensitivity, and the OCR match the CPT test results best when the parameters Nkt, Ns, and k are 15, 6, and 0.3, respectively. The final determination of the ultimate pile capacity depends on the soil’s mechanical properties and the pile type and design. The effects of wave surge and wind loading should also be taken into account in offshore engineering.

ANALISA STABILITAS KELONGSORAN LERENG TERBATAS DENGAN PROGRAM BANTU SOFTWARE GEOSTUDIO 2007

<p>Penelitian ini membahas tentang analisa mekanisme gerakan longsor yang terjadi pada areal sekitar lokasi dusun Bidadari, desa Leubok Pusaka, kecamatan Langkahan, kabupaten Aceh Utara, Kondisi bentang alam yang cukup curam dan kondisi tanah yang kurang stabil, menjadikan tanah di areal lokasi merupakan tanah yang berpotensi longsor. Analisa stabilitas lereng difokuskan pada areal 3 lokasi pengamatan, lokasi titik 01 dan 02 mewakili kelongsoran B-B dan titik 03 dan 04 mewakili kelongsoran lokasi C-C dan titik 05 dan 06 mewakili daerah kelongsoran A-A. Berdasarkan hasil pengujian lapangan sondir (<em>CPT test</em>) dan geoslistrik (<em>geosismis</em>) diperoleh data tentang lapisan tanah berupa <em>silty clay, verystiff,</em> berupa lanau-kelempungan-kerikil, lanau-pasir dan lapisan bebatuan. Untuk mengetahui kemantapan lereng (<em>slope stability</em>) digunakan program bantu Geostudio 2007, metode <em>Morgenstern Price. </em>Hasil analisa menunjukkan bahwa nilai faktor keamanan lereng pada lokasi B-B sebesar 2.54&gt;1.5 (relatif aman), pada lokasi C-C sebesar 1.07&lt;1.5 dan pada lokasi A-A sebesar 1.15&lt;1.5. Kedua lokasi ini menunjukkan nilai factor stabilitas lereng kurang dari yang dipersyaratkan dengan kondisi lereng yang berpotensi terjadi longsor. Selain itu hasil analisa resiko bagi pemukiman dan kondisi bangunan serta kemantapan badan jalan masih berada dalam taraf beresiko menengah dan beresiko tinggi. Disarankan penanganan lereng yang berpotensi longsor dapat dilakukan dengan beberapa alternative, seperti memproteksi lereng dengan tembok penahan tanah (<em>retaining wall</em>), memasang turap (<em>sheet pile</em>), beronjong (<em>gabion</em>) dan memberi perkuatan lereng (<em>geotextile</em>). Dari beberapa metode proteksi tersebut, cara yang paling mudah dalam pelaksanaan adalah dengan memasang <em>sheet pile</em> dari baja galvanis hingga kedalaman20 meter melewati bidang gelincir telah dapat meningkatkan nilai faktor keamanan &gt; 1.5</p>

Analiza kalibracji wyników sondowań CPT z próbnymi odwiertami kolumn przemieszczeniowych CMC

The issue of calibration of the CPT results with test drillings of controlled modulus columns (CMC) columns is widely used in Poland, due to the analogy of drilling parameters for this type of geotechnical research. The values and types of drilling parameters used to correct perform of the calibration depend on the type of the machine executing displacement columns. The issue of calibration is accompanied by problems and technical details that may determine its proper performance. Presentation of three theoretical approaches to searching for one parameter corresponding to the cone resistance chart from the CPT test was developed based on literature and many years’ experience of Menard Polska executing ground improvement in CMC columns technology.

Initial DPSH Soil Test Results with Accelerometer Installed in the Probe Cone

Dynamic penetration test (DPSH) is one of the large amount of soil in-situ tests are known. In world practice, this method usually used for granular soil investigations although it could be applied in cohesive soils. Correlation of received DPSH test results with soil properties is complex and often not reliable. Especially it becomes obvious after application in cohesive soil analysis. In most cases, correlation depends on soil response to dynamic cone penetration and deformation of dynamic sounding equipment. Measurement of cone accelerations allows precisely evaluate loss of hammer energy, displacement of the cone during strike and other parameters. Correlation of DPSH (measured acceleration of the cone) and CPT test results are presented in this article. In this article also presented studies of possibilities to determine dynamic soil characteristics.

Penetration Testing of Liquefaction Potential of Ashes due to Seismic Load

Geomaterials with typical low unit weight and high porosity are significantly prone to liquefaction as a result of dynamic – seismic load. Investigation of geomaterials that are prone to liquefaction due to seismic load can use certain SPT and CPT penetration tests. The method of investigating liquefaction caused by seismic activity was developed based on numerous penetration tests of sandy or silty–sandy soils and was elaborated in detail at the Workshop on Evaluation of Liquefaction Resistance of Soil, NCEER, Salk Lake City, USA, 1996. In the present paper, the results of penetration CPT test conducted at the ash impoundment in Zemianske Kostoľany are analyzed using methodology NCEER.