bluuebunny/crossref_metadata_2025 huggingface dataset:
A Numerical Computation Method for Pipe Cooling Concrete Temperature Field
Authors: Jiang Yu Song , Pan Li Tan , Su Chao
Published: June 2011

Based on the coupled thermal-fluid pipe element, a numerical computation method for concrete temperature field with pipe cooling is proposed in this paper. This method has both the high efficiency of equivalent negative heat source method and the high precision of cooling pipe discrete element method. The theory and detailed steps of the method are introduced. Then the validity and accuracy of the proposed method are demonstrated by an engineering example of concrete ship lock which is better consistent with the measured results.
Research on Settlement and Wavy Failure of Road on Very Soft Soil Foundation
Authors: Yan Shu Wang , Zhang Li Li , Sun Li Qiang
Published: June 2011

Soil foundation in Tianjin Harbor is formed by hydraulic filled materials strengthened by vacuum preloading method, which is still with lower strength and larger compressibility. Large settlement and wavy failure of the roads constructed on such soil foundation are often taking place after two or three years of construction, because of the heavy vehicles running on the roads with high frequency. In order to deal with the existing problems of constructing roads on such very soft soil foundation, the following work is carried out: the displacement characteristics of roads constructed on very soft soil foundation are identified; the design methodology of constructing roads is discussed; the settlement of the constructed roads is calculated with FE methods and the mechanism of wavy failure of the roads on very soft soil foundation is analyzed.
Coupling Analysis and Application of Strata Information and Exploration Information of AGI High-Density Resistivity Measurement System
Authors: Li Chang Hong , Cheng Yan , Zhang Lei
Published: June 2011

According to the study of electrical properties of geological bodies crust, different instruments electric field is measured through the case, then the distribution of the electric field is studied in order to understand the situation of deep underground geological principles. The unknown bodies underground, cave, mined-out areas, ground water detection of two typical survey lines are detected with AGI high-density resistivity measurement system, which the three selected acquisition mode are selected, the sectional drawing of two-dimensional inversion is obtained by data collected processing; the coupling analysis is detected in exploration information and strata Information according to the corresponding geological profile, both high resistance and low resistivity anomalies of the underground and the character of the corresponding space area are accessed; the possibility and ease of the ground surface collapse of different anomalies is pointed out according to the surface geological information and the situation of surface subsidence.
Considerations of Technology Management for Safety Hearing to Schematic Design of Timbering System for Retaining and Protecting for Foundation Pit Excavation in Guangzhou Region
Authors: Zheng Jian Ye , Wu An Li
Published: June 2011

Environmental & structural safety hearing to schematic designing of timbering system for retaining and protecting for foundation pit excavation in Guangzhou region, as a method of compliance control of designing, shows some controversy and compulsory. Technological and management disagreements reconciliation on environmental and structural safety of timbering system is expected through the safety hearings. For timbering system, empirical design takes the role of conceptual design, and boundary condition recognition, construction influence consideration and countermeasure deficiency concerning has to be emphasized during empirical designing experiences. Opportunities for researches also originate from the problems appeared or questions brought forth during the safety hearings. It is necessary to carry out pertinent mechanical analysis to rule-of-thumb measures. Efficiency and fairness is highly required for available process of technology management of finding and confirming suitable engineering technical solutions within the safety hearings.
Study on Acoustic Emission and Failure Modes of Rock in Uniaxial Compression Test
Authors: Zhang Ji Liang , Li Chang Hong
Published: June 2011

Based on uniaxial compression test, the mechanical properties and acoustic emission characteristics of rock had been obtained, including the relationship between AE and time, AE and stress level, and so on, in the whole process of rock failure. Research shows AE rate of rock has the subparagraph features obviously. There are three obvious AE sections for the higher strength elastic-brittle rock: First section is compaction stage, corresponding stress is 10% of compressive strength of rock; Second section is crack-development stage, corresponding stress is 80% of compressive strength; Third section is rupture stage, corresponding stress is the compressive strength. Furthermore, AE signals for the rupture stage is strongest. The law is still correct in cycle loading conditions. However, the subparagraph phenomenon isn’t clear for elastic-plastic rock, and the AE peak is lagging behind the ultimate strength of rock, the AE signal in the decline stage of strength is the most intensive and strong. The lagging phenomenon is due to X-shear rupture model of soft rock. The significant stress concentration in cone tip between the two relative extrusion cones leads to local rock broken seriously. Then, many acoustic signals have been observed.
Study on Soil Permeability Coefficient on CPTU Model Test
Authors: Tang Yan Chun , Meng Gao Tou , Mao Qiu Feng
Published: June 2011

Through analyzing excess pore pressure dissipation datum measured by CPTU probe and pore pressure mini- transducers on CPTU model test, the permeability coefficient of soil of CPTU model test has been computed. According to Strain Path method based on Terzaghi consolidation theory, computation formula of soil horizontal permeability coefficient on CPTU model test has been acquired; on CPTU model test dissipating time of 50% degree of consolidation which has been used as calculation standard to compute horizontal permeability coefficient has been acquired by normalized excess pore pressure dissipation curves based on excess pore pressure dissipation datum; through a series of indoor variable head permeability tests, the permeability coefficient of remolded soil of CPTU model groove sampling by horizontal and vertical direction has been acquired, and the results show that horizontal permeability coefficient is about 1.62 times greater than vertical permeability coefficient on indoor variable head permeability test, and large difference between horizontal and vertical permeability property of remolded clay soil on CPTU model test has been existed; compared with the value of two test methods, the value of horizontal permeability coefficient acquired by CPTU model test is roughly an order of magnitude greater than the value of horizontal permeability coefficient acquired by indoor variable head permeability test. The achieved result can provide a foundation for further study for CPTU mechanism.
Study on Shear Rate Effects of Reticulate Red Clay
Authors: Li Jian Zhong , Tang Xi Qing
Published: June 2011

Direct shear tests were performed to study the shear rate effects of reticulate red clay around Dongting Lake. In the direct shear tests, four sets of undisturbed specimen of reticulate red clay were sheared under the different vertical pressure of 50kPa, 100kPa, 200kPa and 300kPa. Specimens were sheared with six different shear rates of 0.04mm/s, 0.02mm/s, 0.01mm/s, 0.007mm/s, 0.004mm/s and 0.003mm/s under each vertical pressure. Test results show that: (1) shear strength of reticulate red clay increases along with the vertical pressure; (2) shear rate effects of reticulate red clay are affected by vertical pressure significantly; (3) due to its reticulate structure of reticulate red clay, it shows some differences in shear rate effects comparing with other clay.
Study on Sulfate-Attack of Slag-Based Geopolymer Concrete
Authors: Wang Qing , Ding Zhao Yang , Li Lin , Da Jing , Sui Zhi Tong
Published: June 2011

Geopolymer has been attracted world attention as a potentially revolutionary material that is one of the ideal substitutes of portland cement. Fundamental studies on geopolymer are increasing rapidly because of its potential commercial applications. However, little work has been done on its erosion resistance of sulfate. In this paper, slag and metakaolin as source materials, different modules of water-glass as activator were used to prepare slag-based geopolymer which was then prepared to make slag-based geopolymer concrete. Linear expansion rate and mass loss of concrete were used as indicators to explore different erosion rules of slag-based geopolymer concrete which was long-term immersed in the 5% ( by mass ) Na2SO4 solution. Comparative experiments were also done between slag-based geopolymer concrete and ordinary cement concrete. The results showed that geopolymer concrete had excellent sulfate resistance performance, linear expansion rate and mass loss rate of geopolymer were 0.024% and 0.58% respectively at the soaking age of 49d as the water glass modulus was 1.4 and the water-glass content was 4%. It was also found that the anti-sulfate ability of geopolymer concrete is much better than that of ordinary concrete with the same strength grade.
Research of Accuracy Improving in the Inter-City Railway Settlement Observation
Authors: Li Xian Ju , Ma You Li , Li Si Wei , Peng Chong , Chen Gang
Published: June 2011

This paper first introduces the inter-city railway settlement observation implementation scheme, and then makes a statistics analysis on the monitoring data of Wuhan to Xianning inter-city railway. The conclusion is as follow: the main factors that influence the precision of settlement observation are the misclosures of direct and reversed observations, if they are both at a certain range, all monitoring points’ mean square errors of height would reach 0.1mm. Finally summarizes some methods that can improve the precision of settlement observation, in the actual work they make very good effect.
Research on Post-Peak Characteristics of Elastic-Plastic Strain-Softening Model Based on Mohr-Coulomb Strength Criterions
Authors: Niu Shao Qing , Yang Shuang Suo , Cui Lei
Published: June 2011

Considering the characteristic that rock mass can transform from brittleness to plasticity and the dynamic change of post-peak strength parameters of the rock mass, the invariability of elastic modulus and poisson's ratio, constitutive model of rock mass could be described with the characteristic that strength parameters obey different Mohr-Coulomb failure criterions under different plastic strains. This model may reflect the post-peak subsequent characteristics of rock mass and the fact that rock mass can transform from brittleness to plasticity with the increase of confining pressure. Numerical calculation is applied to simulate the triaxial compression test under different confining pressures and underground engineering example, which proves that this model has the characteristic of reflecting the damage extent of surrounding rock.
Numerical Simulation of the Successive Penetration of Jacked Pile in Layered Cohesive Soil and Sand
Authors: Zhang Ming Yi , Kou Hai Lei , Zhang Wei
Published: June 2011

Different constitutive models is piecewise adopted including modified Cam clay model in cohesive soil and Drucker–Prager model in sand in order to simulate the penetration of jacked piles with ABAQUS more reasonably in layered soil particularly in interactive cohesive and sandy layered soil. Simultaneously, a series of other measures are taken including smoothing the angular corner between the tip and the shaft of a pile in the penetration process, allowing elastic slip even local detachment in pile-soil interface, making the initial stress equilibrium in layered soil come true by means of unconventional multiple calculation and so on. Combining with engineering example, the process of successive penetration of jacked pile in layered soil of having significantly different properties and stiff soil-interlayer in soft soil is simulated and calculated successfully, reflecting the abrupt change phenomenon of stress around pile and jacking resistance. And so the conclusion of numerical analysis is consistent with the in-situ observations.
Inclined Slice Method for the Calculation of Slope Stability Safety Factor
Authors: Ge Hai Yu , Tu Jin Song , Xia Song , Wang Jian Guo
Published: June 2011

The vertical slice method is generally adopted for calculation of slope stability safety factor. The algebraic expression of the slope stability safety factor Fs is deducted based on the idea of the calculation via the inclined slice method and according to the inclined slice force limit equilibrium conditions. This expression is implicit so that the result can be obtained quickly only through simple iteratives, guaranteeing the convergence. Calculation examples show that the slope stability safety factor Fs derived from this method is very similar with that from conventional methods. which proves that this method is feasible and brings convenience to technical personnel of slope engineering.
Distribution of Chloride Concentration in Modeled Recycled Concrete Simulated by Finite Element Method
Authors: Ying Jing Wei , Chen He Gong
Published: June 2011

Proposed is a simple analytic model that can simulate the chloride diffusion distribution in a modeled recycled aggregates concrete (RAC). In this paper, on the one hand, the RAC is divided into three phases such as normal aggregates, new mortar and old attached mortar; on the other hand, a single aggregates RAC model was built, finite element method (FEM) is used to simulate chloride diffusion process based on the parameters of diffusivities summarized or derived from other literatures. It is found that the chloride concentration distribution in the RAC shows a band-like profile instead of a smooth curve for a homogeneous medium by ten years diffusion, with the bandwidth undulating and narrowing as the diffusion depth increases. The concentration of chloride distribution can be indicated by the different colors and, therefore, the proposed model allows more accurate realization of diffusion process.
The Transient Electromagnetic Response Characteristics of Unfavorable Geological Bodies in Tunnels
Authors: Meng Lu Bo , Li Tian Bin , Duan Zheng
Published: June 2011

A numerical model of Transient Electromagnetic Methods, which used to detect geological conditions in tunnels, was created by ANSYS finite element software, and the transient electromagnetic response characteristics of typical unfavorable geological bodies were discussed. The results indicate that the apparent resistivity isoline almost outputs in straight structure, and augments equably with the depth increasing when no unfavorable geological body is in front of the tunnel workface. The apparent resistivity isoline obviously reduces when water-rich karst cave, fault, or fracture exist in the front of the tunnel workface, where water-rich karst cave exists, the apparent resistivity isoline becomes close together, and there is to be an ordered pyramid resistivity-reduced area which can be an evidence of rich water fault. However, it will increase when dry fault or karst cave exist, and the high resistivity area corresponding to dry cave shows some triangles, but this phenomena is hard identified, which need detail analyses according to hydrogeologic data.
Dynamic Response of Pile Groups under Vertical Forces in Saturated Soil
Authors: Zhao Yuan Yi , Hong Tao Zhou
Published: June 2011

Based on Biot’s wave propagation equation and boundary conditions, this paper builds up pile group and soil system used for calculation in 3 dimension models, though mass conservative and motion equation. The results of ground surface movement are obtained under the effect of vertical dynamic force though Newmark direct integration. Compared with the measured results, the numerical outcomes conform accurately. The calculating results show that vibration of ground surface can be affected by several parameters such as soils’ possion ratio, permeability coefficient, different types of pile groups and so on. Different factors have different effects on ground’s surface vibration in both far field and near field.
Study on the Toe Segment Slippage Length for Large Bedded Consequent Slope
Authors: Hu Qi Jun , Xie Qiang , Zheng Li Ning
Published: June 2011

The large bedded slopes are the common engineering geology in mountain areas. In this paper, the influence factors, including the gradients, slope length, thickness of slide body, of the large bedded slopes were analyzed. The influence laws of the toe segment slippage length of the factors were obtained and the computing formulas of the toe segment slippage length were presented. The computing formulas were validated by the data of field survey. The results indicated that the toe segment slippage length which were determined by the slope length (L), thickness of slide body (H) and slope gradient (α) were according with the field survey and had the better safety coefficients.
Influence of Recycled Aggregates Volume Fraction on Chloride Diffusion in Model Recycled Aggregates Concrete
Authors: Ying Jing Wei , Chen He Gong
Published: June 2011

In this paper, the influence of recycled aggregates volume fraction (Fra) on chloride induced permeability of recycled aggregates concrete (RAC) was investigated. Finite element analyses of single modeled RAC with regular aggregate arrangements were performed. The recycled aggregate fraction (Fra ) was varied between 0.38 and 0.63. The finite element method (FEM) were based on a mass diffusion approach in which RAC were simplified as three-phase cylindrical inclusions with 1 mm thickness. The analysis results were interpreted by change of permeability. The results show that the chloride concentration on the corresponding boundary vary wavely in a wide range from from 0.00196603 (mg/mm3) to 0.00238315 (mg/mm3) and increase entirely with the increasing Fra due to the influence of old adhered mortar. The effective chloride diffusivities of RAC and the value of chloride amount increase linearly with the increasing Fra.
Computation of Dynamic Characteristics of Deepwater Group Pile Foundation for Bridges
Authors: Xu Can , Yuan Wan Cheng , Wei Kai , Cheung Pak Chiu
Published: June 2011

In the design of deepwater foundation for bridges, the interaction between water and the structure especially under earthquake motions should be addressed. This paper presents a practical simplified method to analyze deepwater pile group foundation to determine its dynamic characteristics by combining approximate analytical solutions with the finite element method. The applicability of this proposed method is shown in a case study of a nine-pile foundation. Compared with those from complete numerical method, the analysis results from this simplified method are in agreement when the pile cap is not submerged in water. Furthermore when ignoring the vertical hydrodynamic added mass of the pile cap, the vertical vibration mode results are greatly affected, but not for other non-vertical vibration modes. This simplified method is also used in the study of the influence of water on the dynamic characteristics. The deeper the water is, the more obvious the impact of water is, particularly for the pile cap lateral bending modes, and there appears no evident difference for the pile lateral bending modes, on which water effect is stronger than that on pile cap lateral bending mode.
Sensitivity Analysis of Parameters for the Simulation of Thermal Transport in Aquifer: A GSHP System in Chengdu, China
Authors: Zhou Yan Zhang , Wu Rong , Fu Zhi Min , Gui Yue
Published: June 2011

Based on the theory of sensitivity analysis, the local/global sensitivity analysis of parameters for the modeling of thermal transport in aquifer under special groundwater flow and heat source conditions were carried out with the summer running of Groundwater Source Heat Pump (GSHP) system as a study case, by taking the temperature of typical observation points and thermal affected zone (TAZ) of injecting water at the end of summer as the model outputs. The results showed that the sensitivity of each modeling output was various for the different parameter in local analysis. The orders of local sensitivity coefficients of the nine parameters for two modeling outputs were almost coincident. In global sensitivity analysis, the sensitivity of the parameter being investigated was influenced by the different values of other parameters. The two modeling outputs almost had the same variation tendency of global sensitivity with different parameter combinations.
The Qualitative Research of Macro-Micro Association of Sand under the Monotonic Loading
Authors: Liu Wen Bai , Li Ye Xun , Cao Liang
Published: June 2011

By analyzing the association relationships between sand particle mechanics parameters and microscopic characteristics, this paper qualitative establishes the association table including physical and mechanical parameters such as the water content w, void ratio e and shear stress, and micro-parameters of sand particle such as particle number n, long axis L, short axis B, x, y coordinate of the centroid of particle, y-axis projection length, degree of eccentricity and orientation arrangement. Then the macro-micro relationship table of sand was established. The macro-micro relationship table of sand indicated that three micro-parameters of sand particle including particle number n, long axis L, short axis B have closely relationship with the water content w, void ratio e and shear stress. And the qualitative research between the sand particle mechanics and microscopic characteristics laid the foundation for the macro-micro association research.
Analysis of Mechanical Characteristics of Site Experiment on Supporting Structure in Gypsum Breccia Tunnel
Authors: Sun Ming Lei , Li Hong Jian , Liu Zhi Chun
Published: June 2011

Gypsum breccia is a kind of soft rock-hard soil, and its component is complex. It has poor cementation, low intensity, strong water reaction, slight expansibility and corrosion. During the tunnel construction of gypsum breccia stratum, the mechanical characteristic of supporting structure is very complex. In order to ensure the safety, reasonability and economy of tunnel support system, it is important to acquire the information on displacement and stress of surrounding rock and support system. Two test sections are selected to monitor. Based on the measured data, the distribution characteristics and the time variation law of different kinds of support in gypsum breccia stratum are studied, including surrounding rock pressure, axial force of rock bolt, support pressure and stress. Such conclusions can be got: When strengthened lining (16# I-steel) of the V-grade surrounding rock used, support system performs well; but the stiffness of primary support is not enough if grillage lining is used. Growth of surrounding pressure is for a long time, which shows that the rock mass has Flow characteristics. Especially the surrounding rock pressure increases continuously. The spatial distribution is random, and the value is large. The stiffness of support system should be strengthened. Most blots at the waist arch are compressive. Bolts at the foot arch and sidewall are under tension. The maximum is nearly 124kN. Contact pressure between primary support and secondary lining at the sidewall is higher than that at arch parts. Steel frame stress comes up to 80% of the maximum within 20 days. Excavation of invert has great influences on stress state of surrounding rock and support system.
Failure Mechanism of Jinjiang Riverbank Based on Geotechnical Properties of Soil
Authors: Chen Chuan Sheng , Wen Shi Zhi
Published: June 2011

In this paper, concerning the geotechnical properties and erosion circumstances of Jinjiang riverbank of Yangtze River, field on-site investigation and soil laboratory tests were conducted. Study results reveal that the soil of Jinjiang riverbank contains mostly the silt particles with 24% of clay content, the unconfined compressive strength of the soil decreases rapidly and permeability have a significant increase with the small change in water content, which are considered to be primary factors of occurrence of riverbank collapse when flooding occur. In addition, it is cleared that collapse process of riverbank are mainly due to the formation of tension crack and toppling behind the bank face.
Analysis of Supporting Rock Structure during Overlying Strata Movement in Shallow Seam Stope
Authors: Li Qing Hai , Yang Ren Shu , Guo Dong Ming , Qin Zhong Cheng
Published: June 2011

Based on existing models of main roof structure, combined with results of field observations, this paper put forward model of supporting rock structure during overlying strata movement in shallow depth. Through force and sliding instability analysis of the structure, it is obtained the relationship between block sliding and block’s lumpiness i and rotation angle θ, and determined a proper formula for calculating support resistance, and obtained the relationship between support resistance and block’s lumpiness i and rotation angle θ, which provides a theoretical basis for roof control and supports selection during shallow seam mining.
The Finite Element Analysis on Foundation Supported with Composite Soil Nailing
Authors: Fu Yu Yong , Yan Shu Wang
Published: June 2011

This article adopts the general finite element analysis software——ANSYS to do the numerical analysis and research on some Composite Soil Nailing. The Drucker-Prager model modified with depth was adopted as the constitutive model. The article presents a lot of numerical calculations and analysis, researching the effects of excavation order, nailing length and nailing obliquity to the horizontal displacement of foundation wall, surface sedimentation and rise of the foundation bottom, giving some useful conclusion which can be used as the references to the design and construction of foundation supported with Composite Soil Nailing.
Computer Simulation of the Shaking Table Tests on Harder Soil-Structure Interaction System
Authors: Li Pei Zhen , Meng Jing , Zhao Peng , Lu Xi Lin
Published: June 2011

Shaking table test on soil-structure interaction system in harder site condition is presented briefly in this paper. Three-dimensional finite element analysis on shaking table test is carried out using ANSYS program. The surface-to-surface contact element is taken into consideration for the nonlinearity of the state of the interface of the soil-pile and an equivalent linear model is used for soil behavior. By comparing the results of the finite element analysis with the data from shaking table tests, the computational model is validated. Based on the calculation results, the paper gives the seismic responses under the consideration of soil-structure interaction in harder site condition, including acceleration response, contact analysis on soil pile interface and so on.
Development of Information Management System for Submarine Pipeline Investigating and Maintaining
Authors: Liu Run , Wang Rui Feng , Yan Shu Wang , Xu Yu
Published: June 2011

With the development of oil industry, thousands of miles of pipelines for oil and gas transformation have been laid down in Bohai and Southeast Sea in China. By now, some pipelines have been reaching the end of the designed working duration and some have been damaged by fishing or anchoring activities. In order to maintain and repair the old or damaged pipelines, the details of the pipelines, such as the construction date, functions and owners, et al., should be found. It is difficult to collect such information in the conventional manner from the piling up of thousands of documents. Therefore, to develop a computerized database for pipeline investigating and monitoring is an urgent task. The principle and methodology of constructing the management system have been put forward and the configurations and functions of the established system expounded.
Meso-Mechanical Testing Scheme on Rock Meso-Damage Based on Digital Image Processing Technique
Authors: Ni Xiao Hui
Published: June 2011

The failure damage of granite under axial load are caused by the propagation and coalescent of cracks at mesoscale, so it is of important theoretical value and practical significance to to understand the mechnical properties of rock by experimental research on meso damage of granite. The microfracturing process of the pre-crack marble sample on surrounding rock in immerged Long-big tunnel in Jinping Cascade II Hydropower Station under uniaxial compression is recorded by using the testing scheme. According to stereology theory, the propagation and coalescent of cracks at meso-scale are quantitatively investigated with digital technology. Therefore, the basic geometric information of rock microcracks such as area, angle, length, width, perimeter, is obtained from binary images after segmentation. The results show that the new meso-mechanical testing scheme on rock meso-damage could be used to quantitatively analyzed from the geometric information of rock microcracks.
Research on the Cusp-Catastrophic of the Stability of the Red Beds Landslide in Western Yunnan
Authors: Sun Feng , Kong Ji Ming
Published: June 2011

The research is for the firs floods and the post-drought in Yunnan area in 2010. The strong rainfall and the hole pressure change are the red rock landslide most essential factor, so an apex post-modulus which indicates the effect of pore-water pressure on stress—strain curves transition is defined at the first. By combining with the stiffness criterion of landslide is analyzed. Consequently rainfall and other conditions changes have important effects induced landslides. It union research thinks of the elephant mountain landslide area, that red rock landslide slope body displacement and the rainfall amount relations and the slope body full water area compares and the stability of slope coefficient relations, establishes one under the strong rainfall function the red rock landslide cusp sudden change model, the quota and qualitative reveals the strong rainfall to the red rock landslide trigger action. This developed model may carry out some use full knowledge to understand the disaster mechanism and the evolutional or accumulative process of hazard factors in mountain red layer of the slope stability problem, which may mean the further to advance the technique of forecasting, it can provide important reference to the disaster prevention.
Numerical Simulation on Projectile Penetrating Wedge Concrete
Authors: Jiang Guo Ping , Huan Shi , Jiao Chu Jie , Tao Wei Jun
Published: June 2011

The numerical simulation method has been used to projectile penetrating concrete for many years. However, most previous research work has concentrated on the cuboids concrete model. Very few studies have been conducted to investigate the penetration process of complex concrete model. In this paper, numerical simulations of laboratory tests are conducted to show the penetration process of wedge concrete model. A double scalar damage model based on the concept of continuum damage mechanics is applied to modeling the failure of concrete. In the numerical model of wedge concrete, the wedges with different angles are modeled.
Influence of Rock Types on the Penetration by Linear Shaped Charge Jet with Uneven Thickness Clad in Cutting Excavation
Authors: Guo Lian Jun , Fei Ai Ping
Published: June 2011

In order to analysis the crack lengths of the different rocks which penetrated by the linear shaped charge jet with uneven thickness clad for cutting excavation, the ANSYS/LS-DYNA code was used to simulate the penetrating process which three kinds of rocks had been penetrated. The results show that: through simulating the penetrate process by eight kinds of linear shaped charge jet with uneven thickness clad, the longest crack was found in Gneiss, the shortest crack was found in Iron ore and the crack length of Granite in between. For the linear shaped charge in this record, the good effect was obtained through taking the uneven thickness clad which vary rate was 2%.The linear shaped charge jet with vary rate of less than 2% slightly was suitable for Gneiss, the linear shaped charge jet with vary rate of more than 2% slightly was suitable for Iron ore, and if Granite was penetrated by linear shaped charge jet with uneven thickness clad, the shaped charge which has 2% vary rate would be more appropriate. It is believe that through the features of penetrated rocks mentioned in the paper, new rock material can be applied easily for pre-splitting blasting engineering in cutting excavation.
Study on Bearing Characteristics of Large Diameter and Long Rock-Socket Pile of Beipan River Bridge
Authors: Gong Cheng Zhong , He Chun Lin , She Yue Xin , Sun Wen Bin
Published: June 2011

Beipan River Bridge is located on the Beipan River Grand Canyon in the middle of Yunnan-Guizhou Plateau. The bridge pile, diameter of 2.8m, subjects to the vertical load design value of 58000KN, the thickness embedded in the breeze rock more than 85% of pile, was almost a full rock-socket pile, its bearing load was large and embedded in rock deeply. Based on test method of self-balancing, the bearing characteristics of large-diameter rock-socket pile in argillaceous area have been analyzed, including the axial force of pile, side friction, the tip resistance and so on. The results indicated that the bearing characteristics of the part in sock was as same as the friction piles in muddy dolostone area; From the results of test the side friction of pile could be estimated higher in strong weathering argillaceous dolomite area while the friction in weak or puny weathering muddy dolostone was relatively close to the value of exploration reports. Pile tip resistance had a greater potential. Finally, analyzed the measured curve, it could be seen that the calculation of bearing capacity was less than the test result, and the pile foundation was safety enough.
Statistical Analyses of Physical Mechanics (PM) Indexes of Zhejiang Soft Soil
Authors: Guo Jun Ying , Li Rong Ji , Shen Hui Fang
Published: June 2011

Through mathematical statistics analyses of basic PM indexes of Zhejiang soft soil samples, obtained are the statistics of soft soil PM parameters, and hence its engineering geological quality. Through linear regression analyses of the soft soil PM indexes by least square method, obtained is the formula of linear inter-index correlations, and tested is the significance between the linear correlation and parameters. The outcomes of the statistical regression analysis provide reference for a rough inter-calculation among soft soil PM indexes, and for engineering constructions.
Numerical Analysis for Bearing Performance of Flexible Piles Composite Foundation Influenced by Modulus’ Changes
Authors: Tan Feng Yi , Wang Xin Zhi
Published: June 2011

The bearing performance of composite foundation improved by flexible piles was influenced by changes of cushion’s modulus, the modulus ratio between soil on bottom of pile and soil surrounded pile, which was analyzed by the finite element method. Results showed that: 1.For single pile, by increasing of cushion’s modulus, the bearing performance nearby the top of flexible pile increased apparently, and the common tendency of settlement of pile and soil surrounded piles was affected negatively. For multi-piles, the increasing of cushion’s modulus resulted in the increasing of bearing performance and the common tendency of settlement of piles and soil surrounded piles was affected positively. 2.The change of modulus ratio between soil surrounded piles and soil on bottom of piles resulted positively in the change of frictional resistance and end-bearing performance nearby the bottom of single pile and reduced the settlement of composite foundation. But the multi-pile borne absolutely all loading due to the increasing of modulus ratio, and both of piles and soil surrounded piles had the same tendency of settlement.
Study on the Calculation Method of Soil-Nailing for High Soil Slope Based on the Logarithmic Spiral Slippery Fracture
Authors: Yang Meng , Liu Xiao Min
Published: June 2011

This paper introduces a new failure mode pattern of soil slope – the logarithmic spiral slippery fracture. A mathematical model for the logarithmic spiral slippery fracture is established, taking the anti-shear function of the soil-nailing into consideration. The shear of soil-nailing, axial force, and the safety coefficients based on the limiting equilibrium method are derived, leading to an accurate stability analysis of the strengthening of soil slope. A case study shows that the anti-shear function of the soil-nailing can be significant and should not be ignored in engineering design.
Strength Anisotropy of a Tailings Sand and its Effect on Stability of a Tailing Dam
Authors: Chen Rui , Li Zai Hong , Lei Wei Dong , Luo Wen Bin
Published: June 2011

In current engineering practice, the effect of strength anisotropy on stability analysis of tailings dam is often ignored. This paper presents direct shear test results on a tailing sand with different angles between shear direction and bedding plane. It is found that shear strength of this soil is significantly directional dependent. The variations in peak friction angle are about 11o, which is approximately 28.3% of the minimum value. The effect of strength anisotropy on stability of a tailings dam is also investigated. The analysis considering anisotropic strength shows a smaller factor of safety and shallower most critical slip surface as compared with isotropic strength model that is used in current engineering practice. To achieve more accurate stability analysis of tailings dams, it is suggested to take into account shear strength anisotropy of tailings soils.
A Geometric Correction Method in Survey of Geometry Properties of Discontinuities in Rock Masses
Authors: Lei Wei Dong , Zhao Feng , Wang Shui Ping
Published: June 2011

A new geometric correction method in processing close range digital photograph is presented. All the critical steps involved in the geometric correction method are briefed and discussed, including determination of Control Points (CP) on the exposure of the rock mass, projection of the 3-D CPs on the exposure of the rock mass to the projection plane, mathematically solving the transformation matrix, geometrically correcting and resampling the digital photograph. As an illustrative example, the whole process of application of the method for a specific digital photograph taken from an outcrop of rock mass is also presented. It is found that the new geometric correction method is effective and more convincing.
Back Analysis of Initial Stress and Mechanical Parameters in Deep Buried Highway Tunnel
Authors: Deng Xiang Hui
Published: June 2011

The in-situ stress is one of important basic data for stability evaluation, engineering design and construction of tunnels. For southwest high mountain region, the in-situ stress in the site test is very difficult. Thus, for satisfying engineering design and construction, it is necessary to back analyze the in-situ stress. The highway tunnel which locates at the 1# road of Lianghekou hydropower station is researched as the object. Based on measured displacements, the inversion model of initial earth stress is built. By comparing the calculated and measured results, the reasonable horizontal pressure parameters and the modulus of elasticity are confirmed.
Research on Control Technology and Structural Characteristics of Very Instable Surrounding Rocks in Structural Belt
Authors: Zhu Yong Jian
Published: June 2011

According to the actual state of the 1150 horizontal main haulageway of Tailai colliery is in the affected areas of many faults, both on the roof to floor and two sides convergences are about 1000mm,the YTJ20 strata structure detector was used to detect the strata structure character of the roadway roof, it showed the surrounding rock of 1150 horizontal main haulageway is very broken and the maximum failure depth reached to 6m; meanwhile we took 4 group of rock samples from the broken zone to carry out x diffraction, the results showed that the surrounding rock in the broken contained high expansibility rock, so measure of rock surrounding grouting reinforcement was proposed without changing the original supporting parameters. Comparative analysis of rock surrounding reinforcement effect before and after grouting was calculated by FLAC simulation soft. The result shows only supported “bolts + shotcrete layer + cables”, both the deformation speed and deformation amount are very obviously, the community of “rock-support” shows loose and breaking state; But using the combined supporting method of grouting reinforcement and “bolts + shotcrete layer + cables”, the surrounding rock deformation obtained effectively control with less stress release, the community of “rock-support” shows higher integrity degree, It can ensure the safe use of the roadway.
Experimental Study on Structural Properties Influencing on Compressibility of Soft Clay
Authors: Wang Jiang Feng , Li Yong Le , Gao Yan Bin , Huang Zhi Quan
Published: June 2011

Through the undisturbed samples and reconstituted samples for compression test, analyzed and got the characteristics of compression deformation and the influence law of structure properties on soft clay. The s-t curves deformation of reconstituted soil in small loads is the largest, as the load increases, tends gradually to horizontal line, but undisturbed soil deformation is the largest under the condition of a bigger load. Undisturbed soil due to structural exists, its s-lgt curves are divided into three categories according to load level. Thee-lgp curve of soft clay is bounded by structure yield stress very clearly divided into two sections, bute-lgp curve of reconstituted soil is a straight line. Because structure of the reconstituted soil has been destroyed, its law of compression characteristics is comparative markedly. But due to the existence of undisturbed soil structural properties, near the structural yield stress, the compression parameters appear mutations. Research results show that influence of soft clay structural properties on its compression characteristics is not allowed to ignore.
Construction Technique of Cement-Soil Mixing Anchor in Foundation Pit in Soft Soil Area
Authors: Liu Gan Bin , Ye Rong Hua , Xu Li , Shen Xue Yi
Published: June 2011

In this paper, the construction technique of a new soil anchor-the cement-soil mixing anchor, which is applicable in the area of soft clay, is introduced. During the construction of the anchor, the drill pipe and blade is served as a reinforced body and formed an anchorage body with the cement-soil body. The material and making, technics parameters, mechanical equipment and construction requirement of the cement-soil mixing anchor are presented firstly. Then, the uplift tests of the cement-soil mixing anchor are carried out, and the ultimate pullout force which is 1.6 times greater than that of the soil nailing in the same condition is obtained. At last, an application of the cement-soil mixing anchor in a foundation pit is given. The test results shown that the application of the cement-soil mixing anchor can reach the expected reinforcement effect. Therefore, this framework can then be used by design engineers to more confidently estimate the pullout capacity of cement-soil mixing anchors under tension loading.
Research of Controlling for Pile-Anchor Joint Supporting Structure on Deformation of Deep Foundation Pits
Authors: Chen Jin Biao , Hu Qiang , Zhou Yuan Wu
Published: June 2011

The excavation of deep foundation pit is very complex in the field of geotechnical engineering, how to control the deformation of deep foundation pit and protect the environment is of great significance. This paper analyzed the deformation mechanism of pile-anchor joint supporting structure in detail, established a model for deformation controlling based on the reliability theory, and then analyzed the sensitivities of prestressed, pile stiffness, spacing and soil properties to foundation deformation. Combined with an engineering example, this paper verifies the stability and effectiveness of the model for deformation controlling. This study will provide some reference to similar projects.
3D Analytical Solution of Soil Deformation Induced by Shield Tunnelling Construction
Authors: Wei Gang , Hong Jie , Wei Xin Jiang
Published: June 2011

Three-dimensional (3D) analytical solution of soil deformation induced by ground loss in shield tunnelling construction was researched. It is put forward that the ground loss ratio is not a fixed value, but changes in driving direction. The calculation formula of ground loss ratio in driving direction was deduced. Based on two-dimensional (2D) analytical solution of uniform ground movement model of shield tunnelling, the three-dimensional analytical solution of ground deformation induced by ground loss is deduced. The settlement in vertical direction and the displacement in lateral horizontal direction at any point can be calculated; and the method is only applied to the construction phase. In analytical calculation: the predicted soil displacements are in good agreement with the measured values, and the method is easy to use; the closer the soil to tunnel is, the faster the lateral horizontal displacement changes; the extent of change of lateral horizontal displacement in longitudinal direction is smaller than displacement in lateral direction.
The Experimental Study of the Soil Thermal Conductivity Based on the Analysis of Actual Internal Fabric
Authors: Li Xiao Zhao , Cao Liang , Xiao Lin , Zhao Gao Feng
Published: June 2011

Thermal properties are very important physical indices of soils which could be applied to estimate the thermal capacity of environmental control system of underground infrastructures. At present, the existing ideal prediction models of thermal conductivity were not suitable for soil which in fact had very complicated internal fabric. For this purpose, SEM images of soil specimens were taken and digitized with binarizing process by using self-developed software package – ImgAnsys for image analysis, and the treated images were successfully input into ANSYS and analyzed based on the two-dimensional heat transient transferring model. It was found that the simulating results were closely consistent with experimental results, which could illustrate the feasibility of this new experimental method.
Experimental Research on the Engineering Properties of Foam-Improved Red Clay Soil
Authors: Qiao Guo Gang , Yuan Da Jun , Liu Bo
Published: June 2011

Red clay soil is widely distributed in south China, the microstructure of red clay soil was studied applying scanning electron microscopy (SEM), and the X-ray diffraction analysis (XRD) test found that a large number of swelling inducing minerals, for example, montmorillonite, illite-montmorillonite or chlorite-smectite were contained in the red clay soil. Shield tunneling in this kind of stratum is prone to arising “cake” and “arch” phenomena and it prone to lead screw conveyor device unsmooth dumping, so soil improvement measures must be taken. Foam as the most advanced soil conditioner has been widely used in shield construction. Using self-developed foam agent, experimental research on foam conditioning red clay soil was carried out, test results show that foam can not only significantly reduce the soil shear strength, but also can greatly enhance the soil's compressibility and fluidity, which is significant for the smooth dumping and excavation face stability maintenance.
Research on the Criterion and Classification of Swelling Rock
Authors: Zhu Xun Guo
Published: June 2011

Criterion and classification are two important content of swelling soft rock research. On the basis of the study of predecessors’ achievements, the percentage of hydrophilic minerals is considered as a key index of the new standard, and the saturated water absorption, limit swelling increment, limit swelling force are considered as main indexes. Finally, the new standard is used to analyze and study on the projects in references.