Analyse Vertical and Horizontal Coefficient of Consolidation of Nha Be District’s Soft Soil, Ho Chi Minh City

Author(s):  
Nguyen Minh Tam ◽  
Vo Nguyen Phu Huan
2020 ◽  
Vol 54 (1A) ◽  
pp. 1-10
Author(s):  
Vo Nhat Luan

This paper presents the experimental results of consolidation properties of soft soil in Ho Chi Minh City of Vietnam. Forty-two samples were collected from different locations and were determined in the laboratory by Oedometer test. The results showed that the coefficient of consolidation of soft soil varies from 0.052.10-3 to 3.3.10-3cm2/s, otherwise the compression index changes from 0.156 to 1.703, soil is in a normally consolidated or over the consolidated state. These properties also change differently with depth. It also indicated that the compressive index of soft soil has a fine linear relationship with the liquid limit، water content, and void ratio. The coefficient of consolidation of soft soil decreases with the increase of compression pressure. These parameters are basic for calculating the settlement of underground structures in Ho Chi Minh City.


2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Nu Nguyen Thi ◽  
Bui Truong Son ◽  
Do Minh Ngoc

The horizontal coefficient of consolidation is the most important parameter for designing the improvement of soil soft by prefabricated vertical drains (PVDs) combined with surcharge and vacuum preloading. This paper presents the experimental study on the horizontal coefficient of consolidation (ch) of some soft soils distributed in Vietnam. The ch value was determined by the laboratory test and CPTu dissipation test. The laboratory tests included the Rowe consolidation cell test and constant rate of strain consolidation with radial drainage test. Two types of consolidation laboratory tests were performed. The experimental results indicated that the ch value is always larger than the vertical coefficient of consolidation of soil (cv). The ratio of ch/cv depends on the consolidated pressure, type of soil, and the anisotropy of soil. The ratio of ch/cv is different in different types of soft soil in Vietnam. In the normally consolidated state, the ch/cv ratio ranges from 1.35 to 10.59. It was necessary to choose the ch value at the consolidated stress level for calculating the PVD spacing.


2011 ◽  
Vol 250-253 ◽  
pp. 1889-1892
Author(s):  
Yong Mou Zhang ◽  
Jian Chang Zhao

Consolidation coefficient and percent consolidation of soft clay were calculated according to the measured pore water pressure of a project in Pudong Shanghai. Calculated coefficient of consolidation was one magnitude larger than the experimental one. This was in conformity with the actual consolidation process of dynamically-consolidated soft soil.


2016 ◽  
Vol 10 (1) ◽  
pp. 41-50
Author(s):  
Wimpie Agoeng Noegroho Aspara ◽  
Eka Nur Fitriani

AbstractIf a structure for reasons of technical, economic, social, or startegic is to be built on a soft ground, then there are usually two problems to be solved, namely the low geotechnical bearing capacity and large soil deformation with sometimes differential settlement. Pre-compression is a foundation soil compression process with the provision of temporary loading (preloading) before actually constructing a building. Pre-fabricated vertical drain is a synthetic drainage system installed vertically inside soft soil layers. Soil condition at the project activity is a relatively very soft clay soil with relatively high coefficient of consolidation resulting in very long period of consolidation process. Therefore, it is needed advance soil improvement by prealoding of pre-fabricated vertical drain. Spacings of installed PVD vary, those are 50 cm, 100 cm, 150 cm, and 200 cm with a pattern of triangles and rectangles. Based on the analytical calculation, it is resulted that optimum PVD distance to achieve 90% consolidation is 150 cm with a triangular pattern. The time of consolidation was achieved within four months. AbstrakKetika suatu struktur karena alasan-alasan teknis, ekonomi, sosial, atau strategis terpaksa didirikan di atas tanah lunak, maka biasanya ada dua masalah geoteknik yang harus dipecahkan yaitu daya dukung yang rendah dan penurunan serta beda penurunan yang besar. Prakompresi adalah suatu proses pemampatan tanah pondasi dengan jalan pemberian pembebanan sementara (prabeban/preloading) sebelum konstruksi yang sesungguhnya didirikan. Prefabricated vertical drain (PVD) adalah sistem drainase buatan yang dipasang vertikal di dalam lapisan tanah lunak. Kondisi tanah di lokasi kegiatan relatif sangat lunak dengan koefisien konsolidasi relatif sangat tinggi mengakibatkan proses konsolidasi berjalan relatif sangat lama. Untuk itu diperlukan perbaikan tanah terlebih dahulu dengan prealoading menggunakan PVD. Jarak spasi antar PVD yang dipasang bervaiasi yaitu 50 cm, 100 cm, 150 cm, dan 200 cm dengan pola konfigurasi segitiga dan segiempat. Berdasarkan hasil perhitungan secara analitis didapatkan jarak optimum PVD untuk mencapai konsolidasi 90% adalah 150 cm dengan pola segitiga dengan proses konsolidasi dicapai selama waktu penurunan 4 bulan.


Author(s):  
Rusdiansyah ◽  
Markawie

Research on soil behavior due to changes in heat temperature in the soil mass is still relatively small. Even though, the phenomenon of increasing temperature in the soil mass is frequently occured. For example, there is an increase in temperature in the ground besides the problem of heat propagation under the road due to land fires, as well as the presence of waste heat from nuclear power plant in the soil medium, the operation of electric cables in the ground which causes heat, and the gas pipelines and oil pipes embedded in the ground, which generates heat around it, as well as thermal energy storage that are embedded in the soil. This research was conducted to get answers to how the behavior of the curve of the clay soft soil consolidation is due to changes in temperature. Mainly to get knowledge about the effect of temperature on changes in the value of mechanical parameters of soil consolidation, such as clay soft soil compression index (Cc), swelling index (Cs), volume change coefficient (mv), coefficient of consolidation (Cv), and hydraulic conductivity (k) of clay soft soil. In conducting the research, the material used was clay soft soil in undisturbed condition originating from a swampland locating in South Kalimantan, Indonesia, while the main tool used was a modified consolidation test device by adding an artificial heating device whose temperature could be adjusted with a temperature control device and temperature sensor. The temperatures applied to the test specimens were 40oC, 60oC 75oC, and 85oC. The results showed that changes in temperature in the soil could affect the compressibility of the soil, where the higher the temperature (heat) of the soil, the greater the soil compressibility. The increase in temperature in the soil causes an increase in the value of soil compressibility parameters such as the soil compression index (Cc), the coefficient of consolidation (Cv), and the swelling index (Cs). The value of compression index (Cc) of clay soft soils has a greater increase than the increase in other compressibility parameters when the temperature of clay soft soil increases (hot). In addition, the presence of high soil temperatures (hot conditions) in the soil can reduce changes in soil volume, where the volume change coefficient (mv) of clay soft soil tends to decrease if the soil temperature increases. Changes in soil temperature also affect soil permeability, where the seepage properties of clay soft soil tend to increase along with an increase in temperature in the soil.    


2020 ◽  
Vol 30 (06) ◽  
Author(s):  
NGUYEN QUANG DUNG ◽  
LE BAO QUOC ◽  
NGUYEN DUC TAM

Due to economic development and traffic congestion constraints, HCM City has implemented urban railways since 2007 and is currently constructing the underground metro line No 01. So far, general constructions and tunnel in particular in Vietnam is a complex issue, especially in the specific soft soil conditions of Ho Chi Minh City. In order to study the behavior of the tunnel during the earthquake, this paper compares an Imposed Seismic Ground Deformation method (ISGD) and the acceleration diagram method in calculating the tunnel affected by the earthquake in soft soil of the area of Ho Chi Minh city.


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