Research on Mechanism of Consolidating the Saturated Soft Clay with the Application of Pile-Supported Composite Foundation

2012 ◽  
Vol 594-597 ◽  
pp. 370-375
Author(s):  
Zhao Hua Zhang
Keyword(s):  
Pore Water Pressure ◽  
Water Pressure ◽  
Soft Soil ◽  
Soft Clay ◽  
Drainage System ◽  
Single Layer ◽  
Composite Foundation ◽  
Critical Height ◽  
The Stability ◽  
Saturated Soft Clay

In order to reduce both uneven settlements and construction duration, researches on pile-supported composite foundation of highway were carried out. When the groundfill is higher than the critical height（1.35 times space between piles）, a complete geostatic arch is formed in the pile-supported composite foundation, which could significantly reduce the uneven settlement. Grids installed at the bottom of embankment could markedly reduce the side displacement and increase the stability of embankment, multilayer grids with layout of loose on the top and dense at the bottom prefer to single layer grids. Plastic drainage board makes up well-functioned drainage system, which can shorten the dispersal time of pore water pressure and accelerate the consolidation of soft soil to shorten the construction duration.

Study on Reinforce Saturated Soft Clay Foundation with Dynamic Consolidation by Drainage

2013 ◽  
Vol 438-439 ◽  
pp. 1171-1175
Author(s):  
Zhi Li Sui ◽  
Zhao Guang Li ◽  
Xu Peng Wang ◽  
Wen Li Li ◽  
Tie Jun Xu
Keyword(s):  
Pore Water ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Soft Clay ◽  
Soil Layer ◽  
Good Effect ◽  
Loading Test ◽  
Test Plate ◽  
Dynamic Consolidation ◽  
Saturated Soft Clay

Dynamic consolidation method has been widely used in improving soft land, but always inefficient to saturated soft clay land, which is hard to improve, and even leads to rubber soil. Dynamic and drain consolidation method will deal with it well, with drainage system, pore-water can be expelled instantly from saturated soft clay as impacting. The pore-water pressure and earth pressure test in construction, the standard penetration test, plate loading test, geotechnical test after construction, which are all effective methods for effect testing. There is a comprehensive detection through different depth of soil layer with different detecting means on construction site. The results show that improving saturated soft clay land with dynamic and drain consolidation method has obtained good effect, and the fruit can be guidance for such construction in the future.

scholarly journals Numerical Modelling of Prefabricated Vertical Drain for Soft Clay Using ABAQUS

2015 ◽  
Vol 773-774 ◽  
pp. 1502-1507
Author(s):  
Saiful Azhar Ahmad Tajudin ◽  
Mohd Fairus Yusof ◽  
I. Bakar ◽  
Aminaton Marto ◽  
Muhammad Nizam Zakaria ◽  
...  
Keyword(s):  
Pore Water Pressure ◽  
Water Pressure ◽  
Soft Soil ◽  
Soft Clay ◽  
Elastic Model ◽  
Clay Layer ◽  
Soil Consolidation ◽  
Consolidation Process ◽  
Vertical Drain ◽  
Prefabricated Vertical Drain

Construction, buildings and infrastructure founded on soft clays are often affected by settlement problem. Therefore, Prefabricated Vertical Drain (PVD) is one of the best solutions to accelerate soil consolidation by shortening the drainage path. In this study, numerical investigation was carried out to pursue a better understanding of the consolidation behavior of soft clay improved with PVD. The consolidation process accelerated by PVD with surcharge of 50 kPa was analysed using the ABAQUS software by adopting an elastic model. The aim of this study is to compare the settlement and the required time to fully consolidate the soft soil at different drain spacings (1.0 m, 1.5 m and 2.0 m) for two different thickness of the clay layer. The results shows that the time required to completely consolidate the soft soil for 12 m and 20 m thickness of clay layer with different spacings are in the range of 3 months to 66 months. The settlement rate and excess pore water pressure dissipation are increased when the spacing of the drain closer.

Calculation of Consolidation Coefficient and Percent Consolidation from Measured Pore Water Pressure of Soft Clay

2011 ◽  
Vol 250-253 ◽  
pp. 1889-1892
Author(s):  
Yong Mou Zhang ◽  
Jian Chang Zhao
Keyword(s):  
Pore Water ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Soft Soil ◽  
Soft Clay ◽  
Coefficient Of Consolidation ◽  
Consolidation Process ◽  
Consolidation Coefficient

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.

scholarly journals METODE VACUUM CONSOLIDATION DENGAN PRELOADING UNTUK MEMPERCEPAT KONSOLIDASI TANAH PADA PERUMAHAN DI TANGERANG

2021 ◽  
Vol 4 (1) ◽  
pp. 171
Author(s):  
Jason Sastilaya ◽  
Gregorius Sandjaja Sentosa
Keyword(s):  
Pore Water Pressure ◽  
Water Pressure ◽  
Soft Soil ◽  
Drainage System ◽  
Soil Condition ◽  
Soil Improvement ◽  
Soil Conditions ◽  
Soil Plasticity ◽  
Calculation Results ◽  
Long Time

The expansion of housing in big cities cannot be denied given the rapid population growth in Indonesia. One of the areas that is currently expanding housing is Kosambi City, Tangerang. Soil conditions in Kosambi City are soft soil with high moisture content and soil plasticity, low permeability and soil bearing capacity, and high pore water pressure. This soft soil condition makes the consolidation decline take a very long time. To overcome the problem of the length of time for this consolidation settlement, it is necessary to improve the land. Soil improvement is being carried out, namely the method of vaccum consolidation with preloading. The combination of these methods is carried out by installing a vertical drainage system in the form of prefabricated fabricated drain (PVD) in soft soil, then the initial load is given in the form of preloading on the soil. The calculation results show that the amount of consolidation reduction that occurs when clay soil is loaded with a stockpile of 1.2 m high, a water surcharge of 1.3 m and a vaccum load is 0.3929 m and 0.6968 m for 85 years. The combined method of preloading and PVD is proven to be able to accelerate the time of consolidation, where Preloading and PVD are installed in a triangle pattern between 0.80 m to a depth of 12 m, capable of achieving a consolidation degree of 90% within 8 weeksPerluasan perumahan di kota besar tentu tidak dapat dipungkiri mengingat pesatnya pertumbuhan penduduk di Indonesia. Salah satu daerah yang sedang dilakukan perluasan perumahan yaitu Kosambi City, Tangerang. Kondisi tanah di Kosambi City merupakan tanah lunak dengan kadar air dan plastisitas tanah yang tinggi, permeabilitas dan daya dukung tanah yang rendah, serta tingginya tekanan air pori. Kondisi tanah lunak ini membuat penurunan konsolidasi membutuhkan waktu yang sangat lama. Untuk mengatasi masalah lamanya waktu penurunan konsolidasi ini, perlu dilakukan perbaikan tanah. Perbaikan tanah yang dilakukan yaitu metode vaccum consolidation dengan preloading. Kombinasi pada metode ini dilakukan dengan cara memasang sistem drainase vertikal berupa prefabricated fabricated drain (PVD) di dalam tanah lunak, kemudian diberikan beban awal yaitu berupa timbunan (preloading) pada tanah tersebut. Hasil perhitungan menunjukkan besar penurunan konsolidasi yang terjadi jika tanah lempung dibebani dengan timbunan setinggi 1,2 m, water surcharge setinggi 1,3 m dan beban vaccum  adalah 0,3929 m dan 0,6968 m selama 85 tahun. Metode kombinasi preloading dan PVD terbukti mampu mempercepat waktu konsolidasi, dimana Preloading dan PVD dipasang dengan pola segitiga berjarak 0,80 m hingga kedalaman 12 m, mampu mencapai derajat konsolidasi 90% dalam waktu 8 minggu. 

Experimental Research of Soft Soil Ground Treatment in Yangpu Port by Static-Dynamic Drainage Consolidation

2013 ◽  
Vol 353-356 ◽  
pp. 203-207
Author(s):  
Yong Kang Yang ◽  
Wu Yang ◽  
Chun Yan Feng
Keyword(s):  
Pore Water Pressure ◽  
Water Pressure ◽  
Soft Soil ◽  
Drainage System ◽  
Physical And Mechanical Properties ◽  
High Water ◽  
Surface Settlement ◽  
High Water Content ◽  
Engineering Practice ◽  
Ground Treatment

Yangpu Port has inhomogeneous soft soil with the properties of high water content, high void ratio, high compressibility and low shear strength. Based on soft soil ground treatment engineering practice, the geological characteristics are summarized, the ground treatment methods are comparatively analyzed, static-dynamic drainage consolidation method is chosen to treat the soft soil ground, the reinforcing mechanism of vertical and horizontal drainage system are discussed, the design of drainage system, preloading and dynamic consolidation are researched and the surface settlement monitoring, pore water pressure monitoring, side piling displacement monitoring, laboratory soil test and plate loading tests are carried out. The results show that average surface settlement is 1170.8 mm, the physical and mechanical properties of soft soil are improved and the characteristic value of foundation bearing capacity is greater than 120kPa.

scholarly journals Analytical Analysis and Field Test Investigation of Consolidation for CCSG Pile Composite Foundation in Soft Clay

2013 ◽  
Vol 2013 ◽  
pp. 1-14 ◽  
Author(s):  
Jin Yu ◽  
Yanyan Cai ◽  
Zhibo Qi ◽  
Yunfei Guan ◽  
Shiyu Liu ◽  
...  
Keyword(s):  
Analytical Solution ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Soft Clay ◽  
Measurement Data ◽  
Composite Foundation ◽  
Theoretical Formula ◽  
Low Grade ◽  
Actual Measurement ◽  
Special Cases

Low-grade concrete-cored sand-gravel (CCSG) pile composite foundation is a new kind of composite foundation for thick and soft clay ground treatment. An analytical solution was derived for calculating the consolidation process of this composite foundation by considering coefficients of horizontal permeability in smear zone, the radial flow within the sand-gravel shell, and the impervious property of concrete-cored pile. The results show that Terzaghi’s one-dimensional consolidation solution and the consolidation analytical solution of ordinary composite foundation were special cases of this solution. Curves of the average consolidation degree of the composite foundation under various nondimensional parameters were observed using the program based on the theoretical formula. Meanwhile, a series of in situ measurements including the settlement of pile and soil, the pore water pressure, and the total stress under embankment load were obtained on the CCSG pile composite foundation on a section of Zhenjiang-Liyang highway. The analyzed results show that the new style composite foundation patent technology has many advantages such as small differential postconstruction settlement (differential is not good, small is), reliable quality, high bearing capacity, and stability. And the consolidation of composite foundation is largely affected by the nondimensional parameters. The analytical solution is finally verified with the actual measurement data.

A Monitoring Test Study on Soft Clay Treatment by Preloading with Plastic Drainage Pipe

2011 ◽  
Vol 90-93 ◽  
pp. 245-249
Author(s):  
Yong Mou Zhang ◽  
Jian Chang Zhao
Keyword(s):  
Pore Water Pressure ◽  
Water Pressure ◽  
Soft Soil ◽  
Soft Clay ◽  
Confined Water ◽  
Plastic Pipe ◽  
Test Study ◽  
Layer 4 ◽  
Monitoring Test ◽  
Drainage Pipe

According to the monitoring results of soft clay treated by preloading with plastic drainage pipe, the consolidation settlement effect of soft clay with 50kPa preloading load, 21m plastic pipe, 1.2m and 1.5m distance was compared with that of 30kPa preloading load, 6m plastic pipe, 1.5m and 2.0m distance. The analysis showed that, the preloading method with deep plastic drainage pipe can accelerate the dissipation of excess pore water pressure in deep soft soil. The over-flow penetration may occur in the confined water. The elastic deformation appears and recoveries after unloading. This is not conducive to the consolidation of soft clay layer 4. The plastic drainage pipe whose depth and distance should be 18~20m and 1.5m respectively to the consolidation soft soil in Pudong.

Experimental Study on the Dynamic Characteristics of Saturated Soft Clay Under Bi-Directional Cyclic Loading

2010 ◽  
Author(s):  
Gong-xun Liu ◽  
Mao-tian Luan ◽  
Xiao-wei Tang ◽  
Qing Yang
Keyword(s):  
Pore Water ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Soft Clay ◽  
Cyclic Strain ◽  
Stress Path ◽  
Cyclic Stress ◽  
Cycle Number ◽  
Cyclic Shear ◽  
Saturated Soft Clay

A series of stress-controlled bi-directional cyclic shear tests under isotropic consolidation conditions were conducted for simulating the cyclic stress induced by wave loading. The area bounded by the elliptical stress path was kept unchanged, while the ratio (R) of the axial cyclic shear stress and the torsional cyclic shear stress was changed in order to research the effect of varied two cyclic stress components on the pore water pressure, strength and deformation behaviors of saturated soft clay. The test results show that with a decrease in R, the residual pore water pressure decreases at first and then increases, and it reaches the lowest at R=1 at the same cycle number, while the amplitude of fluctuated pore water pressure decreases all along. The relationship curves between normalized ratio of pore water pressure and ratio of cycle number have significant differences with different R. The cycle number at failure increases at first and then decreases with decreasing R. It reaches the maximum at R=1, indicating that the dynamic strength is the highest when the stress path is close to a circle. The dynamic stress-strain relationship curves with different R indicate that both the axial and the torsional strains caused by the bi-directional cyclic loadings are mainly the cyclic strains, at the same time, the residual strains appear. With decreasing R, the amplitude of axial cyclic strain decreases and the ratio of axial residual strain and cyclic strain increases firstly and then decreases, while the amplitude of torsional cyclic strain increases. The cyclic shear strain is basically symmetric at R=1, while the residual shear strains appear under other conditions.

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