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土压/泥水平衡双模式盾构适应性设计 被引量:9
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作者 王百泉 左龙 +1 位作者 刘永胜 孟鑑先 《隧道建设(中英文)》 北大核心 2020年第S02期314-318,共5页
为解决复杂地质及周边环境盾构设备选型难题,结合多模式盾构的发展与研究现状,对多模式盾构进行了定义与分类,主要分为土压/泥水双模式盾构、土压/TBM双模式盾构、泥水/TBM双模式盾构等几大类型。并结合南宁市轨道交通5号线一期工程,对... 为解决复杂地质及周边环境盾构设备选型难题,结合多模式盾构的发展与研究现状,对多模式盾构进行了定义与分类,主要分为土压/泥水双模式盾构、土压/TBM双模式盾构、泥水/TBM双模式盾构等几大类型。并结合南宁市轨道交通5号线一期工程,对土压/泥水平衡双模式盾构的主要工作原理、特点、适用范围及适应性设计等方面进行了分析,结果表明:土压/泥水平衡模式盾构地质适应性广、设备利用率高、施工成本低,解决了同一区间不同地质环境条件下盾构设备选型的问题,在一定程度上为地质复杂、工程敏感地带提供了一套可靠解决方案。 展开更多
关键词 双模式盾构 土压/泥水 工作原理 适应性
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基于改进喷涌模型的土压/泥水双模盾构合理转换点研究
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作者 张茹玥 邹福清 +3 位作者 方勇 耿芳闯 卓彬 王宇博 《现代隧道技术》 CSCD 北大核心 2024年第1期125-136,共12页
在高、低水位交替地层中掘进时,为兼顾水下盾构隧道施工的安全性与经济性而采用土压/泥水双模盾构机。但在实际工程中,两种模式的切换普遍过于盲目和主观,以致双模盾构机的效用无法充分发挥。以资阳地铁轨道交通工程宝台大道—苌弘广场... 在高、低水位交替地层中掘进时,为兼顾水下盾构隧道施工的安全性与经济性而采用土压/泥水双模盾构机。但在实际工程中,两种模式的切换普遍过于盲目和主观,以致双模盾构机的效用无法充分发挥。以资阳地铁轨道交通工程宝台大道—苌弘广场盾构隧道工程为依托,先通过理论分析确定泥水/土压两种模式切换的原则及依据,后改进喷涌计算模型并结合采用COMSOL Multiphysics进行三维有限元模拟,得到可量化的土压模式盾构机喷涌风险计算和判别的方法以及螺旋输送机相关参数的影响规律。结果表明:经过现场验证,喷涌可以考虑为合理转换点的寻找原则,且改进喷涌模型计算的双模合理转换点明显优于以往的算法,能够更准确地划分出土压模式的风险区间,安全、经济和科学地指导双模盾构机进行模式切换;改进理论公式与三维模拟计算结果的差异均不超过30%且变化规律相似,螺旋输送机孔隙水流量与螺旋输送机筒体直径和螺旋节距呈线性正相关,与螺旋杆轴直径和螺旋输送机长度负相关。 展开更多
关键词 土压/泥水双模盾构 合理转换点 喷涌 螺旋输送机
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Effect of Alkaline-Stabilised Sewage Sludge on Extractable Organic Carbon and Copper in Soils 被引量:4
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作者 LUOYONGMING P.CHRISTIE 《Pedosphere》 SCIE CAS CSCD 2002年第2期97-102,共6页
An incubation experiment was conducted to evaluate the potential for water contamination with sludge-derived organic substances and copper following land application of alkaline-stabilised sewage sludge. Twocontrastin... An incubation experiment was conducted to evaluate the potential for water contamination with sludge-derived organic substances and copper following land application of alkaline-stabilised sewage sludge. Twocontrasting sludge-amended soils were studied. Both soils were previously treated with urban and ruralalkaline biosolids separately at sludge application rates of 0, 30 and 120 t ha-1 fresh product. The air-driedsoil/sludge mixtures were wetted with distilled water, maintained at 40 % of water-holding capacity andequilibrated for three weeks at 4 ℃ before extraction. Subsamples were extracted with either distilled wateror 0.5 mol L-1 K2SO4 solution. The concentrations of organic C in the aqueous and chemical extractswere determined directly with a total organic carbon (TOC) analyser. The concentrations of Cu in the twoextracts were also determined by atomic absorption spectrophotometry The relationship between the twoextractable organic C fractions was examined, together with that between extractable organic C concentrationand extractable Cu concentration. Application of alkaline biosolids increased the concentrations of soil mobileorganic substances and Cu. The results are discussed in terms of a possible increase in the potential forleaching of sludge-derived organics and Cu in the sludge-amended soils. 展开更多
关键词 clay extracts leaching organic matter trace metals
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Mechanized Tunneling in Soft Soils: Choice of Excavation Mode and Application of Soil-Conditioning Additives in Glacial Deposits 被引量:5
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作者 Roll Zumsteg Lars Langmaack 《Engineering》 SCIE EI 2017年第6期863-870,共8页
The history of the formation of the alpine region is affected by the activities of the glaciers, which have a strong influence on underground works in this area. Mechanized tunneling must adapt to the presence of soun... The history of the formation of the alpine region is affected by the activities of the glaciers, which have a strong influence on underground works in this area. Mechanized tunneling must adapt to the presence of sound and altered rock, as well as to inhomogeneous soil layers that range from permeable gravel to soft clay sediments along the same tunnel. This article focuses on past experiences with tunnel-boring machines (TBMs) in Switzerland, and specifically on the aspects of soil conditioning during a passage through inhomogeneous soft soils. Most tunnels in the past were drilled using the slurry mode (SM), in which the application of different additives was mainly limited to difficult zones of high permeability and stoppages for tool change and modification. For drillings with the less common earth pressure balanced mode (EPBM), continuous foam conditioning and the additional use of polymer and bentonite have proven to be successful. The use of conditioning additives led to new challenges during separation of the slurries (for SM) and disposal of the excavated soil (for EPBM). If the disposal of chemically treated soft soil mate- rial from the earth pressure balanced (EPB) drive in a manner that is compliant with environmental legislation is considered early on in the design and evaluation of the excavation mode, the EPBM can be beneficial for tunnels bored in glacial deposits. 展开更多
关键词 Soil conditioning Earth pressure balanced shield Slurry shield Mechanized tunneling
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Strength of copolymer grouting material based on orthogonal experiment 被引量:12
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作者 陈永贵 叶为民 张可能 《Journal of Central South University》 SCIE EI CAS 2009年第1期143-148,共6页
Using the orthogonal experimental design method involving three factors and three levels, the flexural strength and the compressive strength of copolymer grouting material were studied with different compositions of w... Using the orthogonal experimental design method involving three factors and three levels, the flexural strength and the compressive strength of copolymer grouting material were studied with different compositions of water-cement ratio (mass fraction of water to cement), epoxy resin content, and waterborne epoxy curing agent content. By orthogonal range and variance analysis, the orders of three factors to influence the strength, the significance levels of different factors, and the optimized compound ratio scheme of copolymer grouting material mixture at different curing ages were determined. An empirical relationship among the strength of copolymer grouting material, the water-cement ratio, the epoxy resin content, and the waterborne epoxy curing agent content was established by multivariate regression analysis. The results indicate that water-cement ratio is the most principal and significant influencing factor on the strength. Epoxy resin content and waterbome epoxy curing agent content also have a significant influence on the strength. But epoxy resin content has a greater influence on the 7-day and 28-day flexural strength, and waterborne epoxy curing agent content has a greater influence on the 3-day flexural strength and the compressive strength. The copolymer grouting material with water-cement ratio of 0.4, epoxy resin content of 8% (mass fraction) and waterbome epoxy curing agent content of 2% (mass fraction) is the best one for repairing of cement concrete pavement. The flexural strength and the compressive strength have good correlation, and the ratio of compressive strength to flexural strength is between 1.0 and 3.3. 展开更多
关键词 STRENGTH COPOLYMER chemical grouting orthogonal method regression model
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Study on influence factors of cement-stabilized soil compressive strength 被引量:1
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作者 CAI Chengqiu LI Xin ZHANG Jun GUO Qingsong 《Global Geology》 2012年第2期130-134,共5页
The cement dry jet mixing method has been used to reinforce soft cohesive ground to increase the strength of soft cohesive ground and to decrease its deformation. The study briefly introduces the curing mechanism of c... The cement dry jet mixing method has been used to reinforce soft cohesive ground to increase the strength of soft cohesive ground and to decrease its deformation. The study briefly introduces the curing mechanism of cement-soil,presents the factors of influencing on compressive strength,mainly analyses the factors including cement mixing ratio,cement strength grade,curing age,moisture content and soil texture and puts forward some rational proposals at last. 展开更多
关键词 cement-stabilized soil curing mechanism influencing factors compressive strength
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Experimental study on improving collapsible loess with cement 被引量:2
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作者 SHAN Bo WANG Changming +3 位作者 DONG Quanyang TANG Ling ZHANG Guangyi WEI Jiaming 《Global Geology》 2010年第2期79-84,共6页
The collapsibility of loess ground can directly affect stability of subgrade. Therefore, how to adopt practical technical measures to reduce or eliminate its collapse deformation is an important content in foundation ... The collapsibility of loess ground can directly affect stability of subgrade. Therefore, how to adopt practical technical measures to reduce or eliminate its collapse deformation is an important content in foundation design in collapsible loess zone. Selecting collapsible loess from Fuxin-Chaoyang highway in Liaoning, the authors conducted a series of tests for improving loess with cement. The loess in different water content was mixed with the cement in varying proportions, unconfined compression strength for the samples at four different curing periods were tested, and the relationships of improved soil strength among cement mixture ratio and curing periods were analyzed. When the curing periods are certain, the strength of loess increases along with the mixture ratio increases; when the cement mixture ratio is 5%-15%, the scope of increases is quite obvious; when the mixture ratio is greater than 15%, the tendency of intensity increases turns slow. When the mixture ratio for the specimen is certain, the intensity of the test specimen increases along with the curing period increases, the intensity grows obviously in 28 days, and the growth rate is small in 28-90 days, the intensity tends to be steady in the curing period of 90 days. 展开更多
关键词 collapsible loess CEMENT unconfined compression strength
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Strength characteristics of modified polypropylene fiber and cement-reinforced loess 被引量:11
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作者 YANG Bo-han 《Journal of Central South University》 SCIE EI CAS CSCD 2017年第3期560-568,共9页
The reinforcement and stabilization of loess soil are duscussed by using fibers as the reinforcement and cement as the stabilization materials.To study the strength characteristics of loess soil reinforced by modified... The reinforcement and stabilization of loess soil are duscussed by using fibers as the reinforcement and cement as the stabilization materials.To study the strength characteristics of loess soil reinforced by modified polypropylene(MPP) fiber and cement,samples were prepared with six different fiber contents,three different cement contents,three different curing periods and three kinds of fiber length.The samples were tested under submergence and non-submergence conditions for the unconfined compressive strength(UCS),the splitting tensile strength and the compressive resilient modulus.The results indicated that combined reinforcement by PP fiber and cement could significantly improve the early strength of loess to 3.65–5.99 MPa in three days.With an increase in cement content,the specimens exhibited brittle fracture.However,the addition of fibers gradually modified the mode of fracture from brittle to ductile to plastic.The optimal dosage of fiber to reinforce loess was in the range of 0.3%–0.45% and the optimum fiber length was 12 mm,for which the unconfined compressive strength and tensile strength reached their maxima.Based on the analysis of failure properties,cement-reinforced loess specimens were susceptible to brittle damage under pressure,and the effect of modified polypropylene fiber as the connecting "bridge" could help the specimens achieve a satisfactory level of ductility when under pressure. 展开更多
关键词 fiber-reinforced soil cement-stabilized soil LOESS mechanical properties fracture characteristics
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Effect of clay content to the strength of gravel soil in the source region of debris flow 被引量:1
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作者 CHEN Ning-sheng GAO Yan-chao +1 位作者 Yang Cheng-lin HU Gui-sheng 《Journal of Mountain Science》 SCIE CSCD 2018年第10期2320-2334,共15页
The production of runoff in the source area of a debris flow is the consequence of a reduction in soil strength. Gravel soil is widely distributed in the source region, and the influence of its clay content on soil st... The production of runoff in the source area of a debris flow is the consequence of a reduction in soil strength. Gravel soil is widely distributed in the source region, and the influence of its clay content on soil strength is one of the important questions regarding the formation mechanism of debris flows. In this paper, the clay content in gravel soil is divided into groups of low clay content(1%, 2, 5%), moderate clay content(3.75%, 5.00%, 6.25%, 7.5%) and high clay content(10.0%, 12.5%, 15%). Tests of the unconsolidated undrained shear strength and consolidated drained shear strength were performed. The unconsolidated undrained shearing(UU) experiment simulates the rapid shear failure of loose gravel soil under the conditions of brief heavy rainfall. The consolidated drained shearing(CD) experiment simulates creep failure of consolidated sediment during extended rainfall. The pore water pressure first increased and then decreased as the clay content increased, and the increase in pore pressure was relatively high in the gravel soil sample when the clay content is in the range of 3.25-7.50%, and stress in the gravel soil is relatively low for a moderate clay content. Gravelly soils with a moderate clay content are moreprone to debris-flow initiation. This paper presents a mathematical formula for the maximum shear stress and clay content of gravel soil under two conditions. The key processes whereby the soil fails and triggers a debris flow—volume contraction of soil, expansion of clay soil, and rise of pore pressure―cause reductions in the soil friction force and enhancement of the water content in the clay particles, and subsurface erosion of soil reduces the soil viscosity, which eventually reduces the soil strength so that the soil loses its stability, liquefies and generates a debris flow. 展开更多
关键词 Debris flows Gravel soil Clay content Maximum shear stress Pore water pressure
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Assessment of strength development in cement-admixed artificial organic soil with GX07 被引量:1
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作者 李雪刚 徐日庆 荣雪宁 《Journal of Central South University》 SCIE EI CAS 2012年第10期2999-3005,共7页
To explore the stabilization effect of stabilizing agent GX07 on treating organic soil and the influence of organic matter on the strength development of stabilized soil,artificial organic soil with various organic ma... To explore the stabilization effect of stabilizing agent GX07 on treating organic soil and the influence of organic matter on the strength development of stabilized soil,artificial organic soil with various organic matter content was obtained by adding different amounts of fulvic acid into non-organic clay,and then liquid-plastic limit tests were carried out on the artificial organic soil.Meanwhile,unconfined compressive strength(UCS) tests were performed on cement-only soil and composite stabilized soil,respectively.The test results indicate that the plastic limit of soil samples increases linearly,and the liquid limit increases exponentially as the organic matter content increases.The strength of stabilized soil is well correlated with the organic matter content,cement content,stabilizing agent content and curing time.When the organic matter content is 6%,as the cement content varies in the range of 10%-20%,the strength of cement-only soil increases from 88.5 to 280.8 kPa.Once 12.6% GX07 is added into the mix,the strength of stabilized soil is 4.93 times compared with that of cement-only soil.GX07 can obviously improve the strength of cemented-soil and has a good economic applicability.A strength model is proposed to predict strength development. 展开更多
关键词 stabilized soil unconfined compressive strength artificial organic soil stabilizing agent GX07 composite stabilized soil total cement/water ratio
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Production and Properties of Superplasticized Concrete
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作者 Mohamed Attia Abd Elrahman M. A. Imam +1 位作者 Ahmed H. Abdel Reheem Ahmed Mohamed Tahwia 《Journal of Civil Engineering and Architecture》 2011年第4期341-352,共12页
The objective of this research is to study the effect of grinding powdered superplasticizer, Portland cement, sand, and silica fume on the properties of fresh and hardened concrete. Lose Angeles Machine was used to gr... The objective of this research is to study the effect of grinding powdered superplasticizer, Portland cement, sand, and silica fume on the properties of fresh and hardened concrete. Lose Angeles Machine was used to grind these constituents. The program was arranged to determine the effect of cycles' number, superplasticizer type and dosage, silica fume dosage and condition, and gravel to sand ratio on properties of concrete. Naphthalene sulphonated formaldehyde (NSF) superplasticizers in the forms of liquid and powdered were used. Silica fume may be grinded with the other constituents (grinded), or added to concrete mixer (normal). The water/cement (w/c) ratio varied from 0.35 to 0.55 to achieve a constant slump (50-90 mm). Slumps, bulk density and mechanical properties of concrete were measured. Scanning electron microscope (SEM) was also used to show the differences between traditional and superplasticized concrete. The results showed that grinding the mixture enhances fresh and hardened concrete properties. It is also observed that grinding the mixture for 500 cycles is more effective than other numbers of grinding. In addition, superplasticized concrete exhibits compressive strength higher than traditional one at varied ages. Moreover, using powdered superplasticizer has a remarkable effect on enhancing concrete properties rather than using it in a liquid form. A dosage of 1% by weight of cement gave the highest results of compressive strength. Silica fume has an essential role in improving concrete strength and durability since it acts as very efficient void filler and as a super pozzolana. SEM observations illustrate that grinding the mixture enhances transition zone (TZ) properties and makes it denser. On the other hand, grinded mixture can be packaged in bags and transported for use in crowded cities, and so, enhances quality control, since the only requirement to obtain superplasticized concrete is to add water and gravel. This technique has many benefits such as; saving cement, labor and noise, high quality control, and enhancing concrete permeability and durability. There are many fields of application of superplasticized concrete such as; in locations which are not easily accessible by ordinary concreting techniques, in repairing and strengthen, thin coating, and for small projects when ready mix supply is not feasible. 展开更多
关键词 SUPERPLASTICIZER silica fume Los Angeles Machine cycles' number scanning electron microscope transition zone properties of fresh and hardened concrete.
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Determination of consolidation behaviour of clay slurries 被引量:3
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作者 Khan Faseel S. Azam Shahid 《International Journal of Mining Science and Technology》 SCIE EI CSCD 2016年第2期277-283,共7页
The main objective of this study was to determine the consolidation behaviour of clay slurries.A finegrained clay with high consistency limits(W_L = 180%,w_P= 120%) was investigated using conventional oedometer and be... The main objective of this study was to determine the consolidation behaviour of clay slurries.A finegrained clay with high consistency limits(W_L = 180%,w_P= 120%) was investigated using conventional oedometer and bench-top centrifuge tests.Results indicated that the slurry had an apparent preconsolidation(due to initial conditions,electrochemical interactions,tortuous drainage,and thixotropic strength) from e = 5.7 to e = 5.5 followed by virgin compression.Likewise,the low hydraulic conductivity(10^(-10)-10^(-12) m/s) was due to low porosity(small pore throats) and high tortuosity(long flow paths).Unlike consolidation of soils,the c_v and m_v decreased with increasing σ' but increased with increasing e and k.The data from the two tests correlated well in the range of σ' = 10-65 kPa,e = 5.5-3.86,k= 1.7 × 10^(-10)-5×10^(-11) m/s,F_c = 1-40 MN.New equations were developed to correlate the consolidation parameters(e,σ',k) with F_c.The deviation of k beyond 40 MN(e = 4.65) was due to deviation from the initial straight line portion of the settlement curve in the centrifuge test. 展开更多
关键词 Clay slurry Consolidation Conventional oedometer test Bench-top centrifuge
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High-Volume Fly Ash Concrete-A Relevant Step to Sustainable Development
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作者 Malgorzata Lelusz 《Journal of Environmental Science and Engineering(A)》 2014年第5期257-267,共11页
HVFA (high-volume fly ash) concrete could be a sustainable way for by-product utilization to conserve natural resources and protect environment. HVFA concrete can play the role of a high-performance material that ma... HVFA (high-volume fly ash) concrete could be a sustainable way for by-product utilization to conserve natural resources and protect environment. HVFA concrete can play the role of a high-performance material that may be comparable to the conventional Portland cement concrete. The results of the research programme concerning the relationships between the composition of concrete (w/b ratio, fly ash content and type of cement) and their physical and mechanical properties are presented and discussed in the paper. It is found that the introduction of high-volume fly ash into concrete has caused a decrease in compressive strength at the early age of storage. The significant increase in strength was observed between 28 days and 90 days of curing. The high-volume fly ash concretes were characterized with lower water absorbability and sorptivity than control concrete. 展开更多
关键词 Fly ash concrete high-volume fly ash strength development.
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Analysis on effective stress formula and consolidation of gassy muddy clay
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作者 徐浩峰 应宏伟 +1 位作者 谢新宇 谢康和 《Journal of Central South University》 SCIE EI CAS 2014年第4期1594-1599,共6页
In order to found an applicable equation of consolidation for gassy muddy clay, an effective stress formula of gas-charged nearly-saturated soils was introduced. And then, a consolidation equation was derived. Subsequ... In order to found an applicable equation of consolidation for gassy muddy clay, an effective stress formula of gas-charged nearly-saturated soils was introduced. And then, a consolidation equation was derived. Subsequently, supposing soils were under tangential loading, the expressions of pore water pressure were presented. The analytic solution of pore water pressure was attempted to be validated by the measured values in a real embankment. The parameters in the expressions of pore water pressure were gotten by the method of trial. The result shows that the consolidation model is rational and the analytic solution of pore water pressure is correct. The following conclusions can be made: 1) the influence of bubbles on the compressibility of pore fluid should be considered; 2) the effective stress would be influenced by bubbles, and the consolidation would depend on the compressibility of soil skeleton: the softer the soils are, the more distinct the influence of bubbles is; for normal clay, the influence of bubbles on the effective stress may be commonly neglected. 展开更多
关键词 muddy clay gas bubble consolidation effective stress unsaturated soil
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