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RISS 인기검색어
- 검색키워드
- 저자 : Louis Ge (검색결과 2 건)
- 무료
- 기관 내 무료
- 유료
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Effects of Chemical Stabilizers on an Expansive Clay
Honghua Zhao,Louis Ge,Thomas M. Petry,Yi-Zhen Sun 대한토목학회 2014 KSCE JOURNAL OF CIVIL ENGINEERING Vol.18 No.4
Expansive clays exhibit a high potential for the volume change behavior when the soil moisture changes. The estimated annualcost of the damage to the facilities built on expansive clay in the United States exceeds 9 billion dollars. Because of the physicochemicalnature of the expansive clay, the use of chemical agents to improve their engineering properties is common. This researchinvestigated the effects of chemical agents on an expansive soil from Texas through a laboratory injection method. The agents used inthis study included lime, potassium based agents, and a group of ionic agents. Swelling tests, chemical tests, and soil suction testswere used to evaluate the stabilizing effects of those chemical agents. The testing results indicated that potassium based stabilizer, isan effective stabilizing agent to control the swelling potential of the expansive clay. It can also be injected in the field to build amoisture barrier. The chemical tests on the injected Texas clay showed that the stabilizing mechanism of the ionic agents is possiblythrough the cations’ exchange and the increase of the cations’ concentrations in the soil pore water.
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James C. Ni,Wen-Chieh Cheng,Louis Ge 대한토목학회 2016 KSCE JOURNAL OF CIVIL ENGINEERING Vol.20 No.4
Many underground excavation failures are caused by severe water inflow due to the piping through the opening in the diaphragm wall. The opening can be created by slurry pocket or air pocket during concrete placement by tremie method. This type of defect in diaphragm wall can be detected by sonic logging to show the condition of trench wall and by measuring actual concrete dosage during placing. The same detecting method can be used in two very rare case histories where just-completed primary panels in very soft and thick clay deposit were overturned from the adjacent tremie concreting secondary panel during cold winter. The abnormal increasing concrete dosage and the smooth trench wall profile of secondary panel from sonic logging identify the occurrence of this incident. The causes to trigger this incident include (1) panel size, (2) weather condition, (3) tremie concreting speed of secondary panel, (4) initial and final setting times of concrete in trench, (5) roughness of trench wall, etc. Since the temperature for the two case histories is very low during tremie concreting, the initial setting time of concrete in secondary panel, given by equivalent age maturity function, is much longer than the time to place the concrete in secondary panel. To clarify the failure mechanism, the force-equilibrium analysis of inclined primary panel is conducted taking into account the driving force induced by the concrete pressure in the unset secondary panel and the resistant force given by the adhesion between inclined primary panel and soft clayey soil. It can be concluded from this investigation that the concrete in the secondary panel due to lower concrete curing temperature still remains unset or in plastic form and this will generate much larger driving force to push the adjacent just-completed primary panel to tilt. The measures to prevent similar incidents from happening are also suggested in this paper.
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