Applied Mechanics and Materials Vols. 90-93

Abstract: In order to fully understand and correctly evaluate the stability of overlying strata and surrounding rock, in-situ stress of south main roadway, north main roadway and bypass in shaft station of expanding area, Tao’er coal mine was tested by KX-81-style triaxial stress gauge of hollow inclusion. The test results show that tectonic stress is main in in-situ stress of expanding area, Tao’er coal mine, horizontal principal stress is westeast distribution, 31.13-27.42MPa size, 27.42°-275° direction. Each stress state is not identical, vertical stress is basically slightly less than the weight of the rock covering on unit area. Application of measuring principle of in-situ stress and analysis of field measurement provide a reliable basis for roadway support design and parameters optimization in expanding area of Tao’er coal mine, ensure safety and smooth construction of roadway.

Abstract: Abstract: The numerical simulation of the deformation character in the effect of the unloading action for the surcharge preloading in the heap preloading treated foundation in the Sixin South Road in the New District in Wuhan is done through the finite element analysis software ABAQUS according to the engineering project ,and the following conclusions are gained:(1)on the surface of the foundation, the settlement at the center is the biggest, the settlement decreases with distance from the center of the surface, ,and at about 20m away from the center, the uplift is produced ;(2)after unloading, the resilience emerges in the places where the settlement was produced, and the uplift that was produced drops too;(3)the deformation on the axle of the foundation section at the end of the loading action and that at the end of the unloading action are similar to each other;(4) in the step loading-unloading condition, the deformation curves suit well with the loading-unloading curves.

Abstract: In order to discuss the friction resistance properties between pile and soil, three groups of shear laboratory tests of pile-soil interface are adopted among concrete-soil , steel-soil and plastic(HDPE)-soil, and each test applies six normal stresses. The result indicates that with the growth of normal stress, the shear strength of pile-soil are increased; under the same normal stress, there is little change in frontal parts of curve with shear stress and displacement, but the rest of curve have a striking change along with the increase of normal stress; when the normal stress is less, the shear stress of different interfaces have little change; when the normal stress is greater, it shows that the shear strength of HDPE-soil interface is the greatest.

Abstract: WenXiang tunnel ,one of the tunnels constructed for the ZhengXi Special passenger Railway in china. In this project we have carried out a series of research on optimizing the construction method for shallow and large-span tunnels in loess condition. According to the field monitoring of ground settlement, vault settlement and primary support stress of the tunnel section before tunnelling underneath the LianHuo Highway, the result indicates that soil settlement and primary support stress can not be controlled very well, and current construction program needs to be reformed since it can not meet construction safety requirement. Our synthetical analysis comprises the optimized methods have been used in construction, such as reducing excavation area, increasing excavation steps of pilot tunnel, reserving core soil, closing invert punctually, reinforcing primary support, etc. The security and reliability also has been verified by numerial analysis sofeware FLAC^3D. From feedback of field implement and monitoring result, the effect of optimized method is significant; and all of these methods ensured this tough project implemented successfully. These results derived from our research are subject to a ceritain value that could be referred for future analogous project , in terms of controlling soil settlement and protecting surrouding building facilities.

Abstract: Four concrete beams were cast with normal reinforcement bars. According to different the amount of mounted strengthening, grooves are opened in the concrete cover of tensile region in the concrete beams. Helical Rib Bar（HRB）is inserted in the grooves that is filled with resin. Flexural experimental results indicate that the limit bearing capacity, rigidity and crack resistance of beams strengthened with HRB are all improved obviously. With the increase in the amount of mounted strengthening, the limit bearing capacity of the strengthened beam is improved obviously. In comparison with the contrastive beam, the limit bearing capacity of the beam strengthened with one near-surface mounted HRB is increased by 20.91%, and that of the beam strengthened with two near-surface mounted HRB is increased by 54.55%，and that of the beam strengthened with three near-surface mounted HRB is increased by 90.91%.

Abstract: When bolt is damaged, character of stress is different from character of shear stress integrated bolt. Firstly, Based on the displacement formula of the tunnel surrounding rock，the shear stress and axial force calculation formula of integrated bolt are educed. Subsequence, based on the BOUSSINESG formula of displacement, models on fully grouted bolt shear stress and axial force of uniform rock are educed under pullout load. Consequently, the author deduces shear stress model of bolt damage (completely void of bolt and grouting), combining modes on shear stress and axial force of integrated bolt and shear stress model of bolt under pullout load..

Abstract: Based on the JIAOZHOU bay subsea tunnel in QINGDAO city, with the experimental equation of charge establishment and coherent code, the blasting control technology for blast in shallow tunnel crossing existing buildings of JIAOZHOU bay subsea tunnel is studied. According to a large number of tunnel construction field test data while blasting and the method of regression Analysis, the vibration wave propagation and the calculation parameters of charge quantity is obtained, then calculating the maximum allowable amount of primary explosive segment. Finally the blasting program is optimized. Based on the above methods，house maximum blasting velocity is controlled under 2cm /s . According to the test results of different floors of the building blasting vibration velocity, the velocity of the first floor is greater than the velocity on each floor, so, the velocity of the first floor is recommended to be the control velocity while the maximum charge quantity is calculated. This study is not only useful to ensure the building’s stabilization when blasting in JIAOZHOU bay subsea tunnel but also offers the theoretical and methodological experiences to the similar engineering．

Abstract: The life-span of asphalt pavement is influenced by the strength of subgrade , this paper has discussed the modulus of elasticity of subgrade under different compactness . a example of clay subgrade is gived, the pavement structures and traffic data highway are established according to currently asphalt pavement design specification, the pavement bearing abilitie of different subgrade strength is calculated under different compacting conditions, and also a conclusion has been made that a relation between life-span and strength , the calculating results show that the compactness of subgrade cutting down 1% will lead to pavement reducing 0.65 years, through quantitative analysis, it can be believed that improving compaction of subgrade can obviously prolong asphalt pavement life-span.

Abstract: The author analyzes cause of sunshade survey—a new surveying domain coming into being ,and introduces some methods of sunshade survey applied in Anshan city at present and discusses it, and then puts forward improving some steps of sunshade . To overcome the drawback of method the author concludes establishing method of the digital sunshade system.

Abstract: As an advanced technology in coastal and offshore engineering, wind-driven generator, the suction bucket foundation is one new offshore foundation. It is not only subjected to the long-term action of vertical load(V) induced by all weights of platform and equipment, but also is imposed by both horizontal load(H), moment(M) and torsion(T) caused by wind and wave as well as current. The judgment standard of bearing capacity behavior and practical performance of suction bucket foundation under many freedom loads have been established, which was one key of problems to appraise the stability of foundation. According to the existing results, the features of ultimate bearing capacity and failure envelopes of bucket foundation under combined loads was evaluated in the framework of the general-purpose FEM software package ABAQUS. Results indicated that the failure envelopes of bucket foundation in different loading spaces were plotted, which could be used to evaluate the stability of bucket foundation.