Effect of Curing Temperature on Mortar Based on Sustainable Concrete Material＇s and Poly-Carboxylate Superplasticizer

Nowadays, technologies in construction field have offered several kinds of chemical admixtures, which offer different behaviors at the fresh state of the batch and by consequence, it is resulted with different mechanical behaviors at the solid state of the mix. This study focused on the behavior of a new kind of admixture at fresh and solid states. Currently, the concrete material has become a very expensive material because the high price mostly of aggregates, representing the three quarters of the concrete components. By consequence, it costs money and on the other hand, it produces a lot of wastes. The main aspect which guides this study is to make a kind of concrete based mainly on local material and sustainable concrete material （SCM or waste material）, which is one very abundant material in quality and quantity, under the current tendency the results obtained in this study summarize up the importance of the temperature during the development of the mechanical characteristics of mortar, mainly on compressive strength at age of 28 days. This is in the case of the addition of limestone crushed additive by percentage of substitution.     

Numerical analysis of thermal impact on hydro-mechanical properties of clay

As is known, high-level radioactive waste （HLW） is commonly heat-emitting. Heat output from HLWwilldissipate through the surrounding rocks and induce complex thermo-hydro-mechanical-chemical（THMC） processes. In highly consolidated clayey rocks, thermal effects are particularly significantbecause of their very low permeability and water-saturated state. Thermal impact on the integrity of thegeological barriers is of most importance with regard to the long-term safety of repositories. This studyfocuses on numerical analysis of thermal effects on hydro-mechanical properties of clayey rock using acoupled thermo-mechanical multiphase flow （TH2M） model which is implemented in the finite elementprogramme OpenGeoSys （OGS）. The material properties of the numerical model are characterised by atransversal isotropic elastic model based on Hooke＇s law, a non-isothermal multiphase flow model basedon van Genuchten function and Darcy＇s law, and a transversal isotropic heat transport model based onFourier＇s law. In the numerical approaches, special attention has been paid to the thermal expansion ofthree different phases： gas, fluid and solid, which could induce changes in pore pressure and porosity.Furthermore, the strong swelling and shrinkage behaviours of clayey material are also considered in thepresent model. The model has been applied to simulate a laboratory heating experiment on claystone.The numerical model gives a satisfactory representation of the observed material behaviour in thelaboratory experiment. The comparison of the calculated results with the laboratory findings verifies thatthe simulation with the present numerical model could provide a deeper understanding of the observedeffects.
2014 Institute of Rock and Soil Mechanics, Chinese Academy of Sciences. Production and hosting byElsevier B.V. All rights reserved.     

A Case Study for End of Life Reuse and Recycling Survey Methodologies： The Hollentalanger Cottage

Up to now, reuse and recycling of existing buildings have not been examined widely. This paper discusses the theories, methods and practicalities of buildings＇ end of life with a main focus on planning and managing reuse and recycling of existing buildings. Our aim is the realistic modelling of theoretical scenarios for end of life based on a case study. The methods of building survey, material classification and documentation for reuse, recycling and disposal of existing constructions are presented. Investigations and calculations were done on an existing cottage in the Alps. The ecologically most beneficial disposal phase of the old wooden hut is our main objective. Critical questions arise from the quality of the material and how it can be extracted, separated and balanced in an appropriate way. A systematic survey of the building by inspection of constructions and materials in iterative steps allows a detailed material balance with condition and property information. This information is crucial for scenarios and material flow analysis of demolished and rebuilt building in environmental system analysis. For future planning, the reuse and recycling of existing buildings should be integrated quite early in the planning process so that we can use the materials in the best way.     

A discontinuum-based model to simulate compressive and tensile failure in sedimentary rock

The study presented in this paper discusses a discontinuum-based model for investigating strength and failure in sedimentary rocks.The model has been implemented by UDEC to incorporate an innovative orthotropic cohesive constitutive law for contact.To reach this purpose,a user-defned model has been established by creating dynamic link libraries(DLLs)and attaching them into the code.The model reproduces rock material by a dense collection of irregular-sized deformable particles interacting at their cohesive boundaries which are viewed as flexible contacts whose stress-displacement law is assumed to control the fracture and the fragmentation behaviours of the material.The model has been applied to a sandstone.The individual and interactional effects of the microstructural parameters on the material compressive and tensile failure responses have been examined.In addition,the paper presents a new methodical calibration procedure to ft the modelling microparameters.It is shown that the model can successfully reproduce the rock mechanical behaviour quantitatively and qualitatively.The study also shows how discontinuum-based modelling can be used to characterize the relation between the microstructural parameters and the macro-scale properties of a material.     

A Comparison of Different Approaches in Numerical Modeling of Pavement Granular Material

Modeling pavement granular materials have played through an experimental or numerical approach to predict the a significant role in pavement design procedure. Modeling can be granular behavior during cyclic loading. Current design process in western Australia is based on linear elastic analysis of layers. The analysis is largely performed through a well-known program CIRCLY which is applied to model bound pavement material behavior. The KENLAYER is one of the common pavement software models used for pavement design in the United State which performs non-linear analysis for granular materials. Alternatively, a general finite element program such as ABAQUS can be used to model the complicated behavior ofmultilayer granular materials. This study is to compare results of numerical modeling with these three programs on a sample constructed pavement model. Moreover, a parametric study on the effects of Poisson ratio over the surface deflection of the flexible pavement has been conducted. It is found that increase in Poisson ratio of asphalt layer will increase the surface deflection while the increase in Poisson ratio of granular layers decreases the surface deflection.     

A generalized multi-field coupling approach and its application to stability and deformation control of a high slope

Human activities,such as blasting excavation,bolting,grouting and impounding of reservoirs,will lead to disturbances to rock masses and variations in their structural features and material properties.These engineering disturbances are important factors that would alter the natural evolutionary processes or change the multi-field interactions in the rock masses from their initial equilibrium states.The concept of generalized multi-field couplings was proposed by placing particular emphasis on the role of engineering disturbances in traditional multi-field couplings in rock masses.A mathematical model was then developed,in which the effects of engineering disturbances on the coupling-processes were described with changes in boundary conditions and evolutions in thermo-hydro-mechanical(THM) properties of the rocks.A parameter,d,which is similar to damage variables but has a broader physical meaning,was conceptually introduced to represent the degree of engineering disturbances and the couplings among the material properties.The effects of blasting excavation,bolting and grouting in rock engineering were illustrated with various field observations or theoretical results,on which the degree of disturbances and the variations in elastic moduli and permeabilities were particularly focused.The influences of excavation and groundwater drainage on the seepage flow and stability of the slopes were demonstrated with numerical simulations.The proposed approach was further employed to investigate the coupled hydro-mechanical responses of a high rock slope to excavation,bolting and impounding of the reservoir in the dam left abutment of Jinping I hydropower station.The impacts of engineering disturbances on the deformation and stability of the slope during construction and operation were demonstrated.     

Challenges of Structure in Today＇s Architectural,Economic and Social Context

The recent establishment of a digital culture and society, together with current financial crisis and urgent energetic and climatic needs, has radically changed the architectural scene from the optimism of some years ago to a situation of uncertainty and huge social demands and challenges. In this context, it is suggested to rethink the role of structure in architecture, such as an enabler, a guide and a catalyst. The purpose of this paper is to present the economic, cultural and social context in which architecture develops nowadays. The method, to suggest a discussion on which role the structure may adopt in the architecture to come. The achievement, to highlight its potential to face current requirements and challenges.     

法国利摩日音乐厅

The Concert Hall in Limoges, located in the center of France, returns to the general envelope concept already explored in Rouen, but transforms it through a new material strategy. If, as we have suggested, architecture is the materialization of a concept, what if the concept remains the same, but the material changes? We decided to explore the implications of such a transformation with a new variation on a familiar program.     

Microstructure and anisotropic swelling behaviour of compactedbentonite/sand mixture

Pre-compacted elements(disks,torus) of bentonite/sand mixture are candidate materials for sealing plugs of radioactive waste disposal.Choice of this material is mainly based on its swelling capacity allowing all gaps in the system to be sealed,and on its low permeability.When emplaced in the gallery,these elements will start to absorb water from the host rock and swell.Thereby,a swelling pressure will develop in the radial direction against the host rock and in the axial direction against the support structure.In this work,the swelling pressure of a small scale compacted disk of bentonite and sand was experimentally studied in both radial and axial directions.Different swelling kinetics were identified for different dry densities and along different directions.As a rule,the swelling pressure starts increasing quickly,reaches a peak value,decreases a little and finally stabilises.FOr some dry densities,higher peaks were observed in the radial direction than in the axial direction.The presence of peaks is related to the microstructure change and to the collapse of macropores.In parallel to the mechanical tests,microstructure investigation at the sample scale was conducted using microfocus X-ray computed tomography(μCT).Image observation showed a denser structure in the centre and a looser one in the border,which was also confirmed by image analysis.This structure heterogeneity in the radial direction and the occurrence of macro-pores close to the radial boundary of the sample can explain the large peaks observed in the radial swelling pressure evolution.Another interesting result is the higher anisotropy found at lower bentonite dry densities,which was also analysed by means of μCT observation of a sample at low bentonite dry density after the end of test It was found that the macro-pores,especially those between sand grains,were not filled by swelled bentonite,which preserved the anisotropic microstructure caused by uniaxial compression due to the absence of microstructure collapse.     

Tempo-spatial characteristics and influential factors of rockburst:a case study of transportation and drainage tunnels in Jinping Ⅱ hydropower station

Jinping Ⅱ hydropower station is located in a high in-situ stress region in Southwest China. During the excavations of the transportation and drainage tunnels, more than 460 rockburst events were recorded in the transportation tunnel and 110 in the drainage tunnel, which has a serious and negative influence on the tunnels' construction and the safety of staff and equipment. In the paper, the characters of rockburst patterns are analyzed for the transportation and drainage tunnels. The results are illustrated...     

SAFETY ASSESSMENT OF UNDERGROUND TUNNEL SUBJECTED TO ADJACENT TUNNEL EXPLOSION

A numerical simulation method is proposed to evaluate the underground tunnel safety against explosion in adjacent tunnels. The dynamic constitutive relation used for rock material in the present study consists of a continuum damage model with the damage scalar depending on an equivalent tensile strain, a modified piecewise linear Drucker-Prager strength model allowing for the material strength degradation with damage, and a modified linear equation of state. The numerical model is calibrated by simulation of independent field explosion tests. Parametric study regarding the effect of the adjacent tunnel distance on the dynamic responses of underground tunnel is carried out. Failure zone around the explosion tunnel, and stress, strain and velocity on the adjacent tunnel wall are calculated. Safe separation distance between the adjacent tunnels is predicted and compared with empirical result.     

Behavior of noncircular tunnels excavated in stratified rock masses – Case of underground coal mines

The amount of tunnels excavated along stratified/sedimentary rock masses in Quangninh coal mine area,Vietnam, is gradually increasing. Rock mass in Quangninh is characterized by beddings between rock layers. The behavior of stratified rock masses surrounding the tunnels depends on both the intact rock and the beddings between rock layers. The main characteristics of stratified rock masses that need to be considered are their heterogeneity and anisotropy. Depending on the dip angle of rock layers, movements and failure zones developed surrounding the tunnels can be asymmetrical over the vertical axis of tunnel. This asymmetry causes adverse behaviors of the tunnel structures. The objective of this study is to highlight convergences and yielded zones developed in rock masses surrounding noncircular tunnels in Quangninh coal mine area using a finite element method. The presence of bedding joints is explicitly simulated. The numerical results indicated that with the increase in dip angle of bedding joints, the stress asymmetry over the tunnel vertical axis increases. It gradually leads to an asymmetry of the failure zone surrounding the tunnel. An increase of rock mass quality means a decrease of rock mass sensitivity to the discontinuities. In addition,a dip angle of the bedding joints of approximately 45° could be considered as the critical angle at which the rock mass mechanism changes between sliding and bending.     

Improvement Properties of Cohesion-Less Soil Using Recycled Bassanite

Solid waste management is a serious problem over the world. Therefore, reduction, re-use and recycling of waste have become major issues in recent days. Gypsum waste plasterboard is considered one example of these waste materials. This study evaluates the use of recycled bassanite, which is derived from gypsum waste plasterboard, to enhance the performance of two types of cohesion-less soil. Recycled bassanite was utilized as a stabilizing agent to improve both compressive and splitting strengths of the tested soil. The effect of bassanite content, soil type, water content and curing time were investigated to explore the behavior of treated soil with recycled bassanite. Test results showed that increase of bassanite content is associated with increase in optimal moisture content, while no significant increase in the dry unit weight was observed. Both compressive and splitting tensile strengths enhanced with the additives of recycled bassanite. The increase of bassanite content had a more significant effect on the compressive strength compared with the effect on tensile strength. The use of recycled bassanite to enhance the strength of sandy soil had a more significant effect compared with silty soil. The effect of curing time on the strength of treated samples was more significant in early curing ages compared with late curing ages. The strength decreased significantly in case of stabilized samples prepared with water content at the wet-side of the compaction curve. However, insignificant decrease in the strength of the stabilized sample was detected with moisture content at the dry-side of compaction curve. This research meets the challenges of our society to reduce the quantities of gypsum wastes, producing useful material from waste materials that will help to a sustainable society.     

Some Empirical Examples of Central Place Model in China

At the beginning of 1980s,the Central Place Theory was introduced into China from the West.The authors ofthis article are the initiators of applying this model to China's urban and regional planning as well as to the allocationof commercial activities.Since the commodity economy has been developing in China for thousands of years,most ofthe areas in eastern plains and inland basins of China show the spatial structure of typical central places scene.Duringsome six years,the authors participated in a lot of rural,urban and regional planning projects in which the spatialphenomena and relevant internal mechanism proved this model and its deformation.This paper gives only a few ex-amples of the application of central place theory in China:1.the distribution of rural markets,the empirical study isbased mainly on the situation in Shengfang town and its vicinal area;2.the spatial combination of urban systems,problems about city allocation in North China are emphasized;3.commercial centers in city and the network,a cru-cial study on commercial centers in city and the network,a crucial study on commercial distribution of themetropolis.Beijing is done by using central place model.     

Ground reaction curves for circular excavations in non-homogeneous,axisymmetric strain-softening rock masses

Fast methods to solve the unloading problem of a cylindrical cavity or tunnel excavated in elasto-perfectly plastic, elasto-brittle or strain-softening materials under a hydrostatic stress feld can be derived based on the self-similarity of the solution. As a consequence, they only apply when the rock mass is homogeneous and so exclude many cases of practical interest. We describe a robust and fast numerical technique that solves the tunnel unloading problem and estimates the ground reaction curve for a cylindrical cavity excavated in a rock mass with properties depending on the radial coordinate, where the solution is no longer self-similar. The solution is based on a continuation-like approach(associated with the unloading and with the incremental formulation of the elasto-plastic behavior), fnite element spatial discretization and a combination of explicit sub-stepping schemes and implicit techniques to integrate the constitutive law, so as to tackle the diffculties associated with both strong strain-softening and elasto-brittle behaviors. The developed algorithm is used for two practical ground reaction curve computation applications. The frst application refers to a tunnel surrounded by an aureole of material damaged by blasting and the second to a tunnel surrounded by a ring-like zone of reinforced(rock-bolted) material.     

Axial response and material efficiency of tapered helical piles

Different techniques have been proposed to increase the bearing capacity of open-ended piles.Welding helices to the shaft and tapering the pile shaft could be used simultaneously to enhance the static and dynamic behaviors of these piles.This paper subjects the bearing capacity,stiffness,frictional behavior,and material efficiency of the tapered helical piles to scrutiny.Tapered helical piles are introduced herein as an alternative option to improve the material efficiency of hollow piles.Based on the Taguchi method,a series of experiments was designed and conducted.The axial responses of tapered helical piles are also investigated using finite element analyses.The results derived from loadedisplacement curves and strain gages are used to characterize the axial compression responses of tapered helical piles.The effects of tapered angle,helices diameter and helices distance are examined using dimensionless parameters,and the degree of contribution of these factors is calculated on each of the enumerated variables individually.Experimental results show that the shaft friction resistance of tapered helical piles increases continuously with the pile head settlement.Furthermore,the effect of tapered wall on the shaft friction resistance is more tangible at low stress levels.The results showed that the relative material efficiency factor of the optimum pile could be 2.5 times that of unoptimized pile with a similar quantity of material.     

Vlodern Timber Construction and Products

Everything the practising professional needs to know With increasing ecological awareness on the part of clients, planners and the legislature, timber is again acquiring a greater importance as a building material. The development and use of new wood products and the introduction of stricter regulations to ensure energy-saving forms of construction have completely changed the face of timber building in recent years. The present book provides readers with an overview of modern timber construction and the products now in use.[第一段]     

The Issue of Street Construction in the Transformation of Old City Areas in Medium-and-Small-Sized Cities

Excerpts: The rapid economic development of cities provides the material basis for the transformation of the oldcities. The reconstruction of streets is the first issue being looked at. In the past few years,experiences have beengained and problems encountered. For instance, only some sections of the streets are reconstructed, the scale and de-velopment program of reconstruction are decided without any comprehensive, conceptual planning program, Thispaper attempts to analyse the reasons and defects of the past practice and some suggestions are made on improve-ment measures. It is pointed out in particular, that the transformation of streets should be based in the need, devel-opment potential, characteristics and specific role of the cities in order to enable the streets to be reconstructed incoordination with the transformation of the cities as a whole.     

The Basilica of Santa Maria di Collemaggio in L＇Aquila： Modern Provisional Measures

The case in analysis is Santa Maria di Collemaggio, the church symbol of the town of L＇Aquila and the most important example of Romanesque style in Abruzzi, tragically damaged by the earthquake in 2009. The following paper starts with an accurate analysis of the Basilica, whose historical, stylistical cultural characteristics make it an unicum in the whole urban environment. The authors tried to identify in which way these values have been compromised or altered after the earthquake through several analysis （surveys, historical researches etc.） aiming at the recognition of collapses, the cracks profile, the structural transformations caused by the provisional measures： the goal is to provide a kind of Basilica ＂cognitive manual＂ that will be useful for the future interventions. This first analysis allowed to understand many aspects： on the one hand, the constructive phases and which damages were caused by past careless interventions of restoration, drawing attention to the vulnerability elements of the Basilica; on the other hand, the innovative technologies and materials of the post-seismic provisional measures and their exact location.