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Chen B.,Shanghai University | Chen B.,Quzhou University | Sun D.-A.,Shanghai University | Lu H.-B.,Guangxi Key Laboratory of Geomechanics and Geotechnical Engineering
Yantu Lixue/Rock and Soil Mechanics | Year: 2013

A series of one-dimensional and isotropic compression tests have been carried out on undisturbed and remolded samples of marine soft clay taken from Shanghai and Jiangsu, with different sampling methods. The compression curves, compression index Cc, and swell index Cc are obtained from the tests. According to the normalized compression curves of undisturbed and remolded samples, the effect on compression characteristics of the soil structure is confirmed. The compression curves after the yield stress are extended to determine a reference void ratio e10 * which is used to quantify the fabric simply. Based on the compression index Cc obtained from oedometer tests, the correlation between the compression index Cc and void ratio e10 or reference void ratio e10 * are obtained. From the compression index Cc between oedometer and isotropic tests, it is shown that they are the same on the whole, so the relationship obtained from the oedometer tests can be used for isotropic test results. In terms of the same relationship between the compression index Cc and the reference void ratio e10 * between undisturbed and remolded samples, the characteristics of yielding of structure are discussed. The conclusion that the consolidation pressure is larger than the structure yielding stress, most of the bonding is broken, the difference of compression characteristics is caused by the difference in the fabric, is obtained. The conclusions especially the relationship between the compression index Cc and reference void ratio e10 * provide important reference value for engineering practice.


Liu F.,Tongji University | Liu F.,Guangxi Key Laboratory of Geomechanics and Geotechnical Engineering | Kou X.-Y.,Tongji University | Kou X.-Y.,Shanghai Tunnel Engineering Co. | And 3 more authors.
Yantu Gongcheng Xuebao/Chinese Journal of Geotechnical Engineering | Year: 2013

Due to the scarcity of basic data of hydrate-bearing sediments, a series of triaxial tests are made on synthetic samples of methane-hydrate-bearing and tetrahydrofuran-hydrate-bearing sandy sediments, which are generated using the gas-filtration method and the pre-freezing method, respectively. Attention is focused on the bulk strength of the specimens at different levels of hydrate saturation. The contribution attributed to the back pressure is confirmed by use of the experimental data. The results indicate that the cohesion exponentially increases with the increase of the hydrate saturation. No significant variation is found in the internal frictional angle of the specimens with low to medium hydrate saturation (< 50%), while the angle decreases with the increase of the hydrate saturation due to less particle interlocking at high saturation (> 80%). In addition, the back pressure helps to strengthen the hydrate in voids and thus causes an increase in the strength of the hydrate-bearing specimens.


Yang H.L.,Guilin University of Technology | Zheng Y.,Guilin University of Technology | Zheng Y.,GuangXi Key Laboratory of Geomechanics and Geotechnical Engineering | Li X.K.,Guilin University of Technology | And 3 more authors.
Green Building, Materials and Civil Engineering - Proceedings of the 4th International Conference on GreenBuilding, Materials and Civil Engineering, GBMCE 2014 | Year: 2015

In order to study the double combination structure behavior of Concrete-Partial-filled narrow-width steel box composite beam in negative moment regions, three beams have been tested. Test results show that the behaviors of the continuous beams are improved obviously after filling concrete in cpartial steel box and the beams possess high loading capacity and rigidity and good ductility. Combined with experimental comparison pure shear connection design of composite beams and the influence of relative sliding on deflection, the different reinforcement amount of the crack in the negative moment region of development were analyzed. © 2015 Taylor & Francis Group, London, UK.


Liu Z.,Guilin University of Technology | Liu Z.,Guangxi key Laboratory of Geomechanics and Geotechnical Engineering | Li Y.,Guilin University of Technology | Li Y.,Guangxi key Laboratory of Geomechanics and Geotechnical Engineering
Journal of Natural Disasters | Year: 2014

The influence of wetting-drying cycle action under different pH values condition on shear strength and modulus of compressibility of Guilin red clay was analyzed in this paper. In the same pH value condition, the cohesion of the red clay will be reduced when the number of wet and dry cycles increases. The greater the number of wet and dry cycles, the less the cohesion of the red clay. With the number of wet and dry cycle increasing, the angle of internal friction of the red clay increased. When the number of wet and dry cycles reaches a certain value, the cohesion of the red clay will decrease with the increase and decrease of pH values. When the number of wet and dry cycles is the same, the angle of internal friction of the red clay will increase with the increase of acidity and alkalinity of the solution, but the variation law is not obvious. Under the action of wetting-drying cycle, the modulus of compressibility of the red clay will decrease, while the coefficient of compressibility of the red clay will increase.


Liu F.,Tongji University | Liu F.,Guangxi Key Laboratory of Geomechanics and Geotechnical Engineering | Jiang M.,Tongji University | Zhu F.,Tongji University | Xiao Y.,Tongji University
AIP Conference Proceedings | Year: 2013

Methane hydrate (MH) in voids of marine sediments largely alters the mechanical properties of the host sediments. A bond contact model for such sediments was implemented into the distinct element code to simulate the behavior of a pile embedded in MH rich sea floor under a pullout inclined load. The preliminary results demonstrate that the presence of the hydrates affects the load carrying capacity of the pile, which increases with the increase of the hydrate saturation. The hydrate bonds affect more on the pile capacity of lateral loads than that of uplifting loads. The progressive failure of soils due to pile displacements is accompanied by a growing number of broken bonds. The breakage of bonds initiates adjacent to the upper end of the pile, and grows forming a failure wedge of soils. © 2013 AIP Publishing LLC.


Yang J.,Guilin University of Technology | Yang J.,Guangxi Key Laboratory of Geomechanics and Geotechnical Engineering | Li S.,Guilin University of Technology | Wang Z.,Guilin University of Technology
MATEC Web of Conferences | Year: 2015

Selecting the highway tunnel project in GuangXi province as the experimental research object,using Matlab numerical analysis software to analyze the creep data fitting,this essay concludes that the Generalized kelvin model is proper for creep model.Through converting the creep formula of generalized kelvin model with the third creep formula of implicit creep of ANSYS finite element software implicit creep,it determines the creep model parameters.On this basis,by performing numerical simulations in four different construction methods on expansive surrounding rock tunnel,fill-section excavation,CD excavation,bench cut method and double-side-drift method applied,it researches properties of time-varying mechanical.The results shows that the construction mechanics characteristics of expansive surrounding rock tunnel are effected by time.The deformation of surrounding rock is enhanced with the growth of time,but it tends to be stabilized on the fourth day.Excavation ways have an effect on expansive surrounding rock mechanics.The more one-off excavation rock area digs,the more changes in stress,strain and creep change for the expansive surrounding rock.Among the four kinds of excavation methods,double-side-drift method has best stress form and minimum creep variable. © 2015 Owned by the authors, published by EDP Sciences.

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