Applied Mechanics and Materials Vols. 580-583

Abstract: Characterization of the shear wave velocity of soils is an integral component of various seismic analysis, including site classification, hazard analysis, site response analysis, and soil-structure interaction. Shear wave velocity at offshore sites of the coastal regions can be measured by the suspension logging method according to the economic applicability. The study presents some methods for estimating the shear wave velocity profiles in the absence of site-specific shear wave velocity data. By applying generalized regression neural network (GRNN) for the estimation of in-situ shear wave velocity, it shows good performances. Therefore, this estimation method is worthy of being recommended in the later engineering practice.

Abstract: Calcareous sand is a special marine geotechnical medium that exhibits interesting physical and mechanical properties resulting from its composition and structure. In the current paper, the blasting compression wave (P-wave) attenuation mechanism of calcareous sand under explosion was studied through explosion experiments. The decay law of the P-wave was obtained based on the earth pressure at different distances from the blast center. The results show that, the broken, compress, and damage zones were formed under the effect of blasting load, many particles were broken near the blasting zone. Calcareous sand exhibits strong absorption and attenuation effects on the P-wave because of its particle breakage characteristics.

Abstract: Based on the Biot’s Theory, the dynamic response of non-homogeneous saturated soil has been studied using Helmholtz vector decomposition principle and Exact Dynamic Stiffness Method (EDSM). Reflection and transmission of SH wave in non-homogeneous saturated soil have also been analyzed in considering the continuous variation of physical and mechanical properties of saturated foundation along the thickness. The general calculation formula about the reflection and transmission coefficients of bedrock and free field on both surfaces was achieved. Assuming that the material properties have an exponential law distribution and gradient variation along the thickness-coordinate, the dynamic response of non-homogeneous saturated soils under incident plane SH wave was discussed by numerical examples. The results show that the incident angle, the thickness and heterogeneity index of saturated soil have significant influences on the ratio of the ground displacement and bedrock displacement.

Abstract: The main factors affecting soil compatibility include moisture content, compaction work, soil type, grading and coarse material content etc.. The effects of compaction work are as follows: the stronger compaction work is, the more larger soil dry density is. The optimum moisture content decreases with the compaction work increasing. This paper mainly studies the effect of compaction work to aeolian sand compatibility. Its lay-down thickness is about 30-50cm when we use vibratory roller to compact aeolian sand in practical engineering. This paper analysis’s and studies the maximum dry density and the optimum moisture content of aeolian sand in the middle region of Inner Mongolia, and achieves its lay-down thicknesses are 30cm,40cm,and 50cm respectively at the optimum moisture content. We use 85kg vibration-impact rammer instead of YZ 18 vibratory roller to simulate the aeolian sand compaction effect at the optimum moisture content. The specification does not specify the number of compatibility times, but it is generally 3 to 5 times in the actual project .We choose the most suitable compatibility times and lay-down thickness through anglicizing the Aeolian sand compactness for vibration-impact rammer rolling on eloign sand 3 times,4 times, and 5 times respectively at 3 different kinds of lay-down thicknesses. Through the study of the Inner Mongolia area Aeolian sand, it provides a useful reference for highway and railway construction in the desert area as well as the encapsulated layer thickness of reinforced retaining wall, a new type support structure.

Abstract: The construction techniques and anchoring mechanism of pre-anchoring fissured stope hangingwall of some copper mine in China by fully-grouted cable bolts are explored. The construction stages such as drilling anchor holes, making anchorage cables and cement mortar, grouting, and curing are expounded. A combined action mechanism of pre-anchoring fissured stope hangingwall by fully-grouted cable bolts is presented. The achievements are helpful and beneficial to the design and construction of rock engineering projects which need anchoring reinforcement, such as slopes, tunnels, deep foundation pit, caverns, and underground mining.

Abstract: Understanding the pile behavior and predicting the capacity of piles under horizontal load are important topics in foundation design. In this paper, the mechanical characteristics of single pile under horizontal load is analyzed based on FLAC3D finite difference software, and the load-displacement curve, the bending moment, shear force, soil resistance under all levels of load and the distribution law of p-y curve along the pile shaft are obtained. accordingly the following conclusions can be made: the bending moment of the upper part of pile body is big, the maximum bending moment is at the height of 2~3 meters and it is almost zero below the depth of 9 meters. The bending moment increases with the increase of load, the point of maximum bending moment moves down along the pile body with the increasing of horizontal load. and the location of the point of maximum bending moment moves from 2 meters below the ground to 3 meters below it. The distribution of soil resistance along the pile shaft is a reverse "S", the maximum of pile lateral soil resistance is at the height of about 2~3 meters below the ground.

Abstract: A computer program was compiled based on the C# language of Microsoft Visual Studio 2008 and the principle of simplified Bishop method. The program will calculate the minimum factor of safety, and automatically draw the two-dimensional (2-D) critical slip surface after user input the basic parameters. Through testing a lot of examples, the program has good stability, high precision, fast speed and good visibility.

Abstract: It’s the first application of NEPBS crossing over-shallow-embedded metro in deep soft ground on new Shanghai-Hangzhou passenger dedicated railway (SHPDR) in China. It’s necessary to study the engineering behavior of NEPBS in complex geology field. Long-term observation systems were installed at the typical test sections of SHPDR; Combined with theoretical analysis model, the mechanical properties and deformation laws were analyzed and tested. Measurement results show that the test reinforcement stresses of loading plates and supporting beams are small; the test bending moments agree well with the theoretical bending moments, which are far less than the resistance bending moments; the piles improved the mechanical properties of deep soft ground, so the plate-soil contact stresses are small, the maximum value is 132 kPa; 45 days after the train operation, the post-construction settlement is 1.86 mm; the settlements of individual test points are not yet stable, but they tend toward stability, which can meet the requirements of settlement control of SHPDR.

Abstract: The bearing capacity of residue pile composite foundation formed by deep dynamic compaction, shorted for DDC, is calculated and analyzed by ANSYS finite element software. The analysis results show that pile body and soil between piles have a good coordination, residue pile composite foundation is semi-flexible and semi-rigid and the effect of consolidating foundation is obvious. The purpose of foundation treatment should be taken into consideration primarily to provide reference for future similar projects.

Abstract:

Using constitutive modelling principle of thermodynamics with internal variables, the yield surfaces rotation of saturated sands subjected triaxial compression stress state are justified and explained. The explanation for the yield surfaces rotation of saturated sands prove the correctness and feasibility for the principle of thermodynamics with internal variables to construct elastoplastic constitutive relation of saturated soils.