Predicting the Compression Index of Saturated Reconstituted Contaminated Clays Using Index Properties

Ridong Fan,Jiaping Liu,Songyu Liu,Yanjun Du,Martin Liu,Sunan You 대한토목학회 2021 KSCE JOURNAL OF CIVIL ENGINEERING Vol.25 No.9

An empirical equation was proposed to predict compression index (Cc) of saturated reconstituted contaminated clays. Experimental data from 464 oedometer tests from literature were analyzed, aiding to develop a method for predicting the Cc of saturated reconstituted contaminated clays. The predictive capacity of three existing empirical equations of Cc with either liquid limit (wL), plasticity index (PI) or initial porosity (n0) was assessed. It was found that these equations previously used for clean soils roughly predict the Cc value of saturated reconstituted contaminated clays. To better predict the Cc, a series of empirical equations were established by regression analysis of the experimental data. Finally, the “best” equation was determined by an assessment of goodness of fit.

Compaction and Mechanical Characteristics and Stabilization Mechanism of Carbonated Reactive MgO-Stabilized Silt

Guanghua Cai,Songyu Liu 대한토목학회 2017 KSCE JOURNAL OF CIVIL ENGINEERING Vol.21 No.7

The reinforcement technology of carbonation based on reactive magnesia (MgO) and carbon dioxide (CO2) is a low-carbon and high-efficiency foundation treatment method. This paper investigates the compaction, mechanical and microstructural characteristics of carbonated reactive MgO-stabilized silt with varying MgO-soil ratios, carbonation time and water-soil ratios. The results indicate that the maximum dry density of uncarbonated reactive MgO-stabilized silt increases while the optimum moisture content reduces compared to the parent soil. The unconfined compressive strength of reactive MgO-stabilized soil was found to have increased after CO2 carbonation for several hours. With increasing MgO-soil ratio and carbonation time, the failure mode changes from elasticplastic to brittleness, and the failure strain of carbonated specimens mainly ranges between 0.8% and 1.6% and the ratio of the deformation modulus to unconfined compressive strength is about 30 to 200. The water-soil ratio has a slight influence on the evolution of strength. Scanning Electron Microscopy (SEM) and X-ray diffraction (XRD) analyses have indicated that the carbonation products facilitate the strength growth of reactive MgO-stabilized silt. Thermogravimetric analysis (TGA) shows that CO2 uptake increases with increasing carbonation time and achieves the highest under the MgO-soil ratio of 20%, carbonation time of 6 h, and water-soil ratio of 25%. The stabilization mechanism of carbonated reactive MgO-stabilized silt is proposed according to microstructure analyses, providing a deeper understanding of the application of the reactive MgO carbonation technology in the ground reinforcement.

Evaluation of Geotechnical Parameters of a Lagoonal Clay Deposit in Jiangsu Lixia River Area of China by Seismic Piezocone Tests

Guojun Cai,Songyu Liu,Anand J. Puppala 대한토목학회 2016 KSCE JOURNAL OF CIVIL ENGINEERING Vol.20 No.5

The use of the Seismic Piezocone Test (SCPTU) in geotechnical site investigation offers field assessment on stratigraphy and soil behavior. Compared with some traditional investigation methods such as drilling, sampling and field inspecting method or laboratory test procedures, SCPTU can greatly accelerate the field work and hereby reduce corresponding operation cost. The results of a site investigation on the soft, normally to slightly overconsolidated, Lixia River lagoonal clay deposit underlying several expressway lines, including a seismic piezocone penetration test, undisturbed sampling from an adjacent borehole, and laboratory testing, are reported. The determination of soil profile and the main geotechnical properties is facilitated by the use of seismic piezocone penetration test that can provide up to four independent reading with depth from a single sounding. The coupled use of normalized cone resistance and pore pressure parameter provides a simple and quick soil classification for highly interbedding of Lixia River lagoon ground. Comparison of the results reveals the validity of SCPTU tests to interpret the engineering properties of Lixia River lagoonal clay. These data will also be particularly useful for future local construction work.

Effect of MgO Activity Index on Physicochemical, Electrical and Mechanical Properties of Carbonated MgO-admixed Silt

Guanghua Cai,Songyu Liu,Guangyin Du,Liang Wang 대한토목학회 2019 KSCE JOURNAL OF CIVIL ENGINEERING Vol.23 No.9

The natural soil will have a significant strength improvement when admixed with reactive magnesia (MgO) and subjected to CO2 carbonation, which has been identified as an innovative and environment-friendly technique in the domain of soil treatment. MgO activity has been revealed to have a significant influence on the treatment effectiveness during the carbonation process. With this in view, the effect of MgO activity index on physicochemical, electrical and strength properties of carbonated silt was investigated. Results show that the MgO activity index and initial water-MgO ratio play crucial roles in controlling the aforementioned properties. With the initial water-MgO ratio reducing or MgO activity index increasing, the mass increment ratio, growth rate of unit weight, pH, resistivity, strength and CO2 sequestration increase to different degrees, while the volume increment ratio, water content, specific gravity, porosity and saturation degree decrease. The unconfined compressive strength shows a better linear relation with resistivity, indicating the applicability of resistivity method in the strength evaluation of carbonated MgO-admixed soil. Moreover, the thermal and microstructural analyses have explained the changing mechanism of physicochemical, electrical and strength properties. Finally, the analysis of the CO2 sequestration indicates that the carbonated MgO-admixed silt could achieve a high carbonation degree when the initial water-MgO ratio is less than 2.0, showing the feasibility of MgO carbonation in the CO2 sequestration.

Engineering Properties and Microstructural Characteristics of Foundation Silt Stabilized By Lignin-based Industrial By-product

Tao Zhang,Guojun Cai,Songyu Liu,Anand J. Puppala 대한토목학회 2016 KSCE JOURNAL OF CIVIL ENGINEERING Vol.20 No.7

This paper presents details of a study that deals with determination of engineering properties and microstructural characteristics of a foundation soil (silt) sedimented in Jiangsu Province of China when it is stabilized by lignin-based industrial by-product. A series of laboratory tests were carried out with respect to evaluate the effect of lignin content and curing time on the overall soil properties including Atterberg limits, pH, unconfined compressive strength, stress-strain characteristics, secant modulus, and California bearing ratio. In addition, scanning electron microscopy, X-ray diffraction, and mercury intrusion porosimetry studies were conducted to understand the microstructural characteristics and stabilization mechanism of the stabilized silt. The results reveal that lignin has a great potential to improve engineering properties of silt and shows a promising prospect as a new environmentally friendly soil stabilizer. Curing time and lignin content have significant influence on the basic engineering properties and microstructural characteristics of the lignin stabilized silt. The optimum content of lignin for foundation silt in Jiangsu Province of China is approximately 12%. The precipitated cementing material is formed after stabilization of lignin with a period of curing. The stabilized silt switches over its response from a brittle to ductile material in the presence of lignin. Peak analysis results of the pore-size distribution curves demonstrates that the lignin stabilized silt exhibits bimodal behavior when the lignin content less than 8%, whereas it displays unimodal type when the lignin content is more than or equal to 8%. These observations provide enhanced understanding of lignin-based industrial by-product as a soil stabilizer at the foundation construction.

Field Research on the Treatment of Coastal Phase Liquefaction Foundation with Clay Interlayer Using Resonance Probe Compaction Method

Yuxiao Wang,Guangyin Du,Songyu Liu,Dingwen Zhang 대한토목학회 2022 KSCE Journal of Civil Engineering Vol.26 No.10

The resonance probe compaction (RPC) method is an effective technique for particular soils, which mainly includes sandy and loess. However, the application of RPC on contaioning clay interlayer area has never been seen. In this study, a successful case of using the RPB method to treat the clay interlayer foundation is presented in detail. The test results of Huaiyan high-speed railway construction project are introduced. The test is divided into the laboratory test and the field test, mainly including standard penetration test (SPT), cone penetration test (CPT) and seismic wave cone penetration test (SCPT). The test results indicated that the cone resistance of silt and silty sand layers increased to an average of 2.13 times compared with an average of 4.39 MPa before treatment, and the sleeve friction whose initial average is 54.17 kPaincreased to an average of 1.74 times. The existence of the clay interlayer does not affect the consolidation and drainage of the silt layer and the silt sand layer, and after the construction, the excess pore water pressure around the vibration point can be dissipated by more than 90% within 15 minutes. After reinforcement, the standard penetration number of subsoil, increased by about 15% − 95% compared with an average of 19 blows before treatment and the clay particle content of some clay interlayers are reduced to less than 10%. The shear wave velocity of the subsoil in the treatment depth increased by about 15% − 48% compared with 140 m/s before treatment. The RPC method was successful for the coastal phase liquefaction foundations.

Characterization of Spatial Variability of CPTU Data in a Liquefaction Site Improved by Vibro-compaction Method

Guojun Cai,Jun Lin,Songyu Liu,Anand J. Puppala 대한토목학회 2017 KSCE JOURNAL OF CIVIL ENGINEERING Vol.21 No.1

Vibro-compaction is a ground improvement technique in which the weak or loose soil deposits are compacted by the vibrating probe or vibroflot penetration. The Piezocone Penetration Test (CPTU) has been found to be one of the best methods to assess the effect of ground improvement due to its continuous, reliable and repeatable data collected. The spatial variability of a liquefactionsusceptible site improved by vibro-compaction was assessed using random field theory. The CPTU soundings were conducted to characterize the variation of random field model parameters. Given the relatively high data frequency of the cone tip resistance in vertical direction, the vertical random field parameters are determined with the modified Bartlett random field estimation procedure. Due to the lack of data in horizontal direction, the horizontal random field parameters are evaluated using a less rigorous way of the autocorrelation. It is shown that the normalized cone resistance is a well estimator of spatial variability. The statistical results suggest that both Scale of Fluctuation (SOF) and the Coefficient of Variation (COV) varied in different way after vibro-compaction.

Effect of Chito-oligosaccharide Supplementation on Immunity in Broiler Chickens

Deng, Xingzhao,Li, Xiaojing,Liu, Pai,Yuan, Shulin,Zang, Jianjun,Li, Songyu,Piao, Xiangshu Asian Australasian Association of Animal Productio 2008 Animal Bioscience Vol.21 No.11

This study was conducted to determine the effects of dietary supplementation of either 100 mg/kg chito-oligosaccharide (COS) or chlortetracycline (CTC) with corn-soybean-fish meal on immunity in broiler chickens. A total of 147 one-day old male broiler chicks were randomly allocated to 3 treatments with 7 replicate pens per treatment and 7 birds per pen. The experimental diets consisted of a control diet based on corn, soybean and fish meal without COS and any antibiotic supplement and similar diets supplemented with either CTC (80 mg/kg from d 1 to 21 and 50 mg/kg from d 22 to 42) or COS (100 mg/kg from d 1 to 42). During the entire experimental period, all birds had ad libitum access to diets and water. The main immune organ indices, T-lymphocyte proliferation, serum cytokine concentrations, serum NO level and serum iNOS activity were measured on d 21 and d 42. On d 21, broilers fed 100 mg/kg COS had improved (p<0.01) indices of spleen, thymus, and bursa of Fabricius compared with the control and CTC birds. Birds receiving 100 mg/kg COS had higher (p<0.05) serum concentrations of $IL-1{\beta}$, IL-6, IgM, NO and iNOS than birds on the control treatment. Serum $Ca^{2+}$ level of birds fed 100 mg/kg COS tended to be higher (p = 0.049) than in birds fed CTC. On d 42, the birds fed 100 mg/kg COS had higher (p<0.05) concentrations of TNF-${\alpha}$ and IgM in serum than birds in both the CTC and control treatments. Birds fed 100 mg/kg COS had a higher concentration of IFN-$\gamma$ than the control group. In conclusion, dietary supplementation of COS appeared to improve the immunity of broilers by promoting the weight of the main immune organs, increasing IgM secretion, stimulating microphages to release $TNF-{\alpha}$, $IL-1{\beta}$, IL-6 and IFN-$\gamma$, and activating iNOS to induce NO.

Study of Deflection of Buried HDPE Corrugated Pipeline under the Uneven Settlement of Soil

Wenbo Gu,Kai Wu,Liyuan Tong,Songyu Liu 대한토목학회 2022 KSCE JOURNAL OF CIVIL ENGINEERING Vol.26 No.1

This paper aims to study the deflection of high-density polyethylene (HDPE) corrugated pipeline subjected to differential settlements of the ground using the finite difference method-discrete element method (FDM-DEM) coupling simulation method in 3D. Various physical characteristics of the pipeline, including diameters, corrugations, and elastic modulus have been investigated. Soil particles with different shapes are considered. The variation of soil settlement of soil particles with three different shapes under the uneven settlement condition is studied. The soil arching effects, including positive soil arch and negative soil arch, have been respectively analyzed. The results reveal that the change in pipe corrugation influences the stiffness of the pipe and the friction between the pipe and soil to some extent, which also causes the change of vertical deflection of the pipe. The soil composed of four particles is easier to form soil arch, which makes the soil more self-stabilized, thus alleviating the circumferential deformation of the pipeline.