Hu A.-F.,Zhejiang University |
Rao H.,Zhejiang University |
Rao H.,Shanghai Municipal Engineering Design General Institute Group Co. |
Yuan J.,Zhejiang Province Institute of Architectural Design and Research
Yantu Gongcheng Xuebao/Chinese Journal of Geotechnical Engineering | Year: 2012
As a technique for protection of adjacent buildings, the outrigger-type diaphragm wall been applied in deep excavation engineering. But the worldwide researches in this area are still relatively scarce until now. In extension project of Hangzhou Huanglong Hotel, outrigger-type diaphragm walls are adopted to solve the problem of insufficient rock-socketed depth. And thus the rock-socketed depth of support structures in intermediary weathered rock is ensured. Moreover, the construction difficulty is reduced. Good social and economic benefits are gained. Based on the Huanglong excavation case, a 3-D finite element model is presented to simulate the behavior of outrigger-type diaphragm walls by using the software ABAQUS. The behavior of soil is assumed to conform to the modified Cam-clay model, and the actual construction sequence is simulated. The numerical results and monitoring data in the excavation of lateral displacement are compared. The reasonable stiffness of the section steel in the outrigger-type diaphragm walls is also analyzed.
Wang L.-L.,Shanghai Municipal Engineering Design General Institute Group Co. |
Wang L.-L.,Tongji University |
Chen W.,Hohai University |
Lin T.,Hohai University
Zhongguo Kuangye Daxue Xuebao/Journal of China University of Mining and Technology | Year: 2011
In order to reduce the biological risk caused by bacteria attached to carbon fines (BACF), the characteristics of carbon fine and the bio-chemical mechanism of bacteria were analyzed. Furthermore, the desorption principle of BACF were discussed. Through the orthogonal test and comparative study, a new collaborative method of high-speed centrifugation and desorption agent was developed to weaken various forces between bacteria and fines and to improve the desorption efficiency. Then the suitable conditions about high-speed centrifugation and combination of desorption agent were further optimized. The results demonstrated that desorption efficiency could be improved by 75.6%. The best desorption ratio of BACF was to 15.1 times under the optimum centrifugal conditions, which were high-speed centrifugation (18×103 r/min, 5 min, 4°C and the solution combination (sodium pyrophosphate 0.01%; tris buffer 0.01 mol/L, pH7.0; peptone 0.01%; surface active agent 1 μmol/L; EGTA 1 mmol/L). The bacteria were generally separated from the fines during the experiment. The results were significant in controlling the biological safety in GAC process effluents.
He C.-X.,Shanghai Municipal Engineering Design General Institute Group Co.
Wuhan Ligong Daxue Xuebao/Journal of Wuhan University of Technology | Year: 2011
This study investigates the effects of different aggregate gradations and compaction number on road performance of asphalt mixtures. The dynamic stability, low temperature bending failures strain, soaking marshall stability, AASHTO T283, split strengthen and freeze-thaw split strengthen are used to evaluate the road performance. Three gradations (Sup13, Sup20 coarse and Sup20 fine) and two compaction (100, 125) number were selected. Means comparison using Tukey test is used to analyze. Increasing compaction number would bring on higher dynamic stability, low temperature bending failures strain, split strengthen and freeze-thaw split strengthen. Compared with fine gradation, coarse gradation gives higher dynamic stability, low temperature bending failures strain, split strengthens and freeze-thaw split strengthen under the same compaction number. There are no significant differences between water stability with coarse and fine gradation or different compaction number. Coarse gradation is top-priority compared with increasing compaction number.
Liu K.,Shanghai Municipal Engineering Design General Institute Group Co. |
Zhao C.-F.,Tongji University
Yantu Gongcheng Xuebao/Chinese Journal of Geotechnical Engineering | Year: 2011
The primary goal of this research is to study the influences of different pile-tip soils on the bearing characters of bored piles. Soils laid around and under piles are selected based on characteristics of strata passed through by bore piles in soft soil. Prefabricated model piles are pre-installed onto the pile-tip soils with film around them to remove influences induced by differences in coarse degree and diameter of piles, and to produce unloading effect on piles. Test data are gained after static loading tests on six model piles, and the influences on side resistance are discussed. Relations between side resistance and relative displacement are established and normalized to quantitatively solve the problem. It is concluded that the model tests on the influences of different pile-tip soils on the bearing characters of bored piles are valid, and more test data and project practice are needed to solve this problem thoroughly.
Li X.,Shanghai Municipal Engineering Design General Institute Group Co. |
Shi X.,Tongji University |
Ruan X.,Tongji University
Wuhan Ligong Daxue Xuebao (Jiaotong Kexue Yu Gongcheng Ban)/Journal of Wuhan University of Technology (Transportation Science and Engineering) | Year: 2012
To control cracks and large deflection in long-span concrete bridges, sufficient large-tonnage pre-stressing forces are usually applied in curved bottom slabs. In this case, curved bottom slabs in box girders are under state of high stress and duct opening ratio. Consequently, more serious accidents like concrete near pre-stressing ducts completely damaged and bursts into two parts during the process of closure in main span happen frequently in recent years. In the paper, the whole process of typical burst failure of curved bottom slab in a pre-stressed concrete bridge is reappeared by using facilitated numerical computation analysis in consideration of nonlinear characteristic of materials. The mechanism of crack arises, damage course and actions of different types of reinforcements in bottom slab is quantitatively studied during the construction process.