Applied Mechanics and Materials Vols. 353-356

Abstract: In the past, most of the soil electrical resistivity charts were developed based on stand-alone geomaterial classification with minimal contribution to its relationship to some of geotechnical parameters. Furthermore, the values cited a very wide range of resistivity with sometimes overlapping values and having little significance to specific soil condition. As a result, it created some ambiguities during the interpretation of observations which were traditionally based on qualitative anomaly judgments of experts and experienced people. Hence, this study presents soil resistivity values based on laboratory experiment with a view to predict the soil moisture content and density in loose and dense soils. This study used a soil box and a resistivity meter to test a clayey silt soil, increasing its water usage from 1-3% based on 1500 gram of dry soil. All the moisture contents and density data were observed concurrently with 25 electrical soil resistance observations being made on the soil. All testing and formula used were in accordance with that specified in BS1377 (1990). It was apparent that the soil resistivity value was different under loose (L) and compact (C) condition with moisture content (w) and density (ρ_bulk) correlations being established as follows; ρ_{bulk (C)} = 2.5991ρ^-0.037, ρ_{bulk (L)} = -0.111 ln (ρ) + 1.7605, w_(L) = 109.98ρ^-0.268, and w_(C) = 121.88ρ^-0.363 with determination coefficients, R² that ranged between 0.69 0.89. This research therefore contributes a means of predicting these geotechnical parameters by related persons such as geophysicist, engineers and geologist who use these resistivity techniques in ground exploration.

Abstract: Double-row piles are often used for the large-scale landslide control. The frame double-row piles are the common types. Coupling beam is an important component of frame double-row piles. It plays an important role in transferring landslide thrust. A finite element model of landslide was established to evaluate the effect of section size and length of coupling beam on the internal force of double-row piles. It was found that the internal force of double-row piles increased with the length of coupling beam, and found that it was unfavorable for the moment distribution of double-row piles if the section size of coupling beam was too large or small. Therefore, the reasonable length of coupling beam is equal to the height of the piles section. With the reasonable moment distribution of double-row piles, the section size of coupling beam has an optimum value.

Abstract: Numerical simulation was used to study the relationship between reinforced earth retaining wall gradient and geogrid strain. Research results show that when the load on the wall top is small, the function of geogrids in the upper section of retaining wall is not brought to full play, the angle between potential rupture surface and horizontal plane is small and resembles Rankines active soil pressure rupture surface, and it is far from wall face. When the load on wall top increases, potential rupture surface becomes steep, the distance between the surface and wall face is about one third of wall height. Inclined wall face also displays this property. The gentler the reinforced earth retaining wall gradient is, the smaller the geogrid stress is, and the safer the wall is. However, when gradient drops below 1:0.4, safety increase becomes vague. When wall gradient is 1:0.3, geogrid stress is most uniformly distributed, and thus has the highest use efficiency and the wall is the most cost-effective.

Abstract: As dams approach the end of their design life periods, retrofitting of dams is needed in many cases. For the retrofitting procedure of building a new dam close to the existing old dam without demolishing it, the interaction between the two dams and the unbounded foundation is an important issue to be investigated. The influence of the existing dam on the dynamic response of the newly built dam is examined. Two systems are analyzed, i.e., the new dam-foundation system and the dam-foundation-dam system. For the two systems, modal analysis and time history analysis using the viscous-spring artificial boundary are performed. It’s found that there’re much more vibration frequencies for the dam-foundation-dam system as compared to the new dam-foundation system within the same frequency range. The existence of the old dam also induces one more peak and a wider plateau in the response spectrum of the acceleration time history of the dam crest. However, the maximum stress distribution is not influenced much by the old dam.

Abstract: With the STX-50 pneumatic-typed dynamic triaxial system, the undrained dynamic triaxial tests on the saturated cohesive soil are performed to study the dynamic strength properties. The changing process of the dynamic strength, backbone curve and the soil deformation of the cohesive soil under dynamic load are zoom analysis by stages to get their regularity. It is found that the stage change of the dynamic strength, backbone curve and the soil deformation all exist, which the stage I of the soil deformation has little damage, the stage III is not allowed, the stage II is determined by the importance of the concrete and the sensitive degree to the deformation. In order to analysis the deformation stability and stress stability of the formation in the effect of the dynamic load, provide qualitative and quantitative basis for the soil dynamic study.

Abstract: Based on practical engineering, numerical analysis model was established by using finite element analysis software. The rules about raft settlement, pile-top counterforce, soil counterforce were analysed after variable pile diameter. It is more favorable on settlement and counterforce after variable pile diameter than Original design. There is important academic significance and application value on pile raft foundation optimal design.

Abstract: Based on the unified solution of shear strength in terms of double stress state variables for unsaturated soils, the unified formula of stability coefficient for unsaturated soil slopes under the plane strain condition is derived by Sweden slice method, which considers the effect of the intermediate principal stress rationally. Combining with engineering example, the proposed formula is compared with the one that is on the basis of Fredlund unsaturated soil theory and the influencing characteristics of factors including intermediate principal stress, matric suction, effective internal friction angle and matric suction angle is obtained. The research result indicates that: intermediate principal stress and matric suction have obvious impacts on the stability coefficient for unsaturated soil slopes; the stability coefficient has been increasing with the increase of unified strength theory parameter and matric suction, which proves that the consideration of intermediate principal stress and matric suction can make slopes give full play to their self-stabilities and strength potential, and the yield criterion has great impact on the judgment of slope stability; the stability coefficient also increases nonlinearly with the increase of effective internal friction angle and matric suction angle. The proposed unified formula of stability coefficient for unsaturated soil slopes enjoys a wider application. The stability coefficient for unsaturated soil slopes according to the Fredlund unsaturated soil theory and that for saturated soil slopes are just the special cases. The research result can provide theoretical basis for stability analysis and reinforce design of the unsaturated soil slopes, and it is of great significance to the slope management.

Abstract: Pouring base cushion first and then construct anti-floating anchor to avoid strong weathered diorite prolonged exposure and disintegration. The post-poured wedge concrete resistance to water pressure, the middle concrete pads fixed waterstops, Reinforced fixed seal ring, The cement penetration crystalline deal with concrete construction joints. With polyurethane, BAC waterproof coiled material for anti-floating anchor root waterproof treatment.

Abstract: According to the problem of rock slope deformation, fracture and stability during the transform from open-pit to underground mining at Yanqianshan Iron Mine, using FLAC large deformation mode to analysis mine excavation characteristics about deformation and damage of open-pit slope in different depth. Excavation simulation displays that the softrock of north slope easily to backfall heavily, But unusually form rapid sliding, the influence to underground mining is small, but large number of small crushed stones fill the rock layer, that is unfavorable to control the dilution and loss index. South slope hardrock mass have not appeared large deformation and unitary sliding during primary mining.

Abstract: Based on the engineering tests of muck ground treatment project, the contact stress control valueP_maxf of muck ground is derived and the maximum allowable stress ratio R is defined according to the basic consideration of the muck ground pressure is greater slightly than the bearing capacity characteristic value of muck foundation for many micro fractures can be formed and the ground could keep whole stability at same time. The R and P_maxf can give the reasonable value of the impact loading in static-dynamic drainage consolidation method (SDDCM). It is an effective way to avoid the failure in design and construction as well. In addition, R is the parameter to judge the reinforcement effects of muck foundation. The results of this paper were applied to actual engineering projects and the engineering test data showed the application effects are very good.